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INTRODUCTION

1. Chemical and physical properties of coal dust

Dangerous impact of coal mining in the Kemerovo region

Physiological mechanisms damaging organs

Occupational diseases of coal miners

Sanitary and hygienic standards for coal mining

Means and methods of protection against a harmful factor at work

CONCLUSION

Bibliography

INTRODUCTION

Relevance. The rapid development of the coal industry in the Donbass and other regions of the Russian Federation, the introduction of new equipment and technology in production require workers, engineers and technicians to have clearer knowledge, careful observance of occupational health rules and healthy lifestyles.

Dust exposure miners, metro builders, masons, workers of cement, brick, tile, flour-grinding, sugar factories, road workers, moulders, foundry workers, textile workers, workers of confectionery industries are exposed. Once in the respiratory tract, dust particles cause inflammation of the tissue of the pulmonary vesicles, which leads to the development of connective tissue in them. Broncho-pulmonary diseases of professional etiology continue to be the most important problem in medicine in terms of the amount of social damage caused, which is primarily due to insufficient knowledge of the mechanisms of action of fibrogenic dust of a mixed composition, as well as the action of combined factors of gases, aerosols, etc.

1. Chemical and physical properties of coal dust

Dust is characterized by a set of properties that determine its behavior in the air, its transformation in the body, and the effect on the body. Of the various properties of industrial dust, the chemical composition, solubility, dispersion, explosiveness, shape, electrical charge, and radioactivity are of greatest importance.

The most important properties of dusts are determined directly by their fineness, particle shape, good dissolution properties and unique chemical composition. For the assessment of dust from the hygienic side, the most important feature is nothing more than dispersion.

Dust formation in different mines is not the same and depends on the mining and geological conditions, the microstructure of coal, its hardness, humidity, the conditions of the bed, as well as the method of extracting coal, the mechanisms used, etc. It is shown that on hard coals, the formation of dust is approximately 25% more than on soft ones. Wet coal produces less dust. More dust is formed on steep seams than on gentle ones, which is associated with the descent of coal. Extraction of coal along the cleat (bedding) produces less dust than the excavation against the cleat. The main operations associated with dust emission are coal mining with a combine, seam cutting with a coal-cutting machine, manual and jackhammer breaking, heaping on a conveyor, coal breaking on steep seams with jackhammers, loading coal from a conveyor into trolleys, tunneling machine operation, drilling and blasting, machine rock loading, delivery to the shaft by trolleys, unloading of skips.

In terms of the intensity of dust formation, not all of these operations are equivalent. According to studies, 95% of all dust is generated in the faces. Of the total amount of dust generated, 60% is accounted for by the operation of mechanisms, about 20% - by blasting in the face, 10% - by breaking and 10% - by other works. .

The amount of airborne dust is also different in different mines, depending on the above reasons. The greatest dust content of the air, as a rule, is observed during the operation of combines; in the absence of means to combat dust, its concentrations can reach several grams per 1 m3 of air. The other most dusty operation is the operation of the coal miner, roadheader. Dust concentrations can reach hundreds of milligrams per 1 m3. Up to 1000 mg/m3 can reach the dust content of the air during dry drilling. High dust content is observed during blasting. On steeply dipping seams, large dust formation (several thousand milligrams per 1 m3) is observed when coal is lowered to the loading hatch.

Coal dust is generated during the following production operations:

.Breaking coal with combines and blasting.

.Hole drilling.

.Loading coal by loading machines.

.Transportation of coal by conveyors.

.Loading at loading and unloading points.

Maximum permissible concentrations of coal dust:

The process of grinding dispersed materials is well described by the Rittinger law (the specific power consumption for grinding is directly proportional to the size of the newly formed surface.

Coal dust is well transported by air flow or combustion products. The dust-air mixture forms a very mobile emulsion with the properties of a liquid, and is easily pumped through pipes. In individual dust preparation systems located directly at the steam generator, the concentration of dust in the air mixture is relatively low and usually amounts to |A1 = = 0.5 h-1 kg of dust per 1 kg of air (or gases). In the presence of a central dust plant (CPZ), dust is transported from the bunkers of the CPZ to the dust bins of steam generators at high concentrations (about 30-35 kg of dust / kg of air) through small-section pipelines by transfer pumps, in which the dust is mixed with compressed air having a pressure of 0, 5-1 MPa (5-10 kgf/cm2). Pumping of a highly concentrated dusty air mixture can be carried out over long distances, on the order of several hundred meters.

Factors affecting the explosiveness of coal dust:

1.Explosive concentration of coal dust in suspension is from 16 - 96 g/m3 to 2000 g/m3.

2.The yield of volatile substances is 15% or more.

.The size of dust particles is up to 1 mm, the smaller it is, the more dangerous.

The ignition temperature of coal dust is 750 - 850 0 C. The speed of the blast wave is 1000 m / s. The strongest explosion at a concentration of 300 - 400 g/m3. When the harvester is operating without irrigation, the dust content of the air is 50 g/m3, during the blasting operation it is 300 g/m3. The deposition of coal dust during the operation of a roadheader is at the face - 600 g/m3 per day. When working with a shearer - 900 g/m3 per day. At loading points (transfers) - 100 g/m3 per day. 4. Humidity and ash content - the higher the moisture content and ash content of coal, the less explosive the dust is. The dispersion of dust suspended in the air is mainly high: up to 40-80% of dust particles have sizes up to 1.3 microns, 15-35% - up to 2.6 microns, 5-20% - up to 4 microns and 3-10% - over 4 microns.

2. Dangerous impact of coal mining in the Kemerovo region

coal dust mining disease

The transition of the coal industry to market relations requires the profitable operation of its enterprises. The basis of such work is high-performance and reliable equipment, corresponding to the mining and geological conditions of the occurrence of coal seams. Many mines of Kuzbass are currently equipped with domestically produced mechanized cleaning complexes, in particular, the Yurga Machine-Building Plant (KM-138, KM-142, KM-144). However, there is a steady trend towards the use of imported equipment. As a result of these processes, coal mining enterprises have already become dependent on foreign suppliers, whose services are becoming more expensive, which negatively affects the cost of coal. Approximately the same situation is developing with underground transport equipment, especially with belt conveyors. A serious negative consequence of the increase in coal is the further deterioration of the environment in the Kemerovo region, which is not the most prosperous region for life anyway. In the Siberian regions (the cities of Omsk, Tomsk, Novosibirsk, Krasnoyarsk, Kemerovo) there are enough conversion machine-building plants capable of providing coal mining enterprises with high-performance and reliable equipment. It is necessary to reorient these enterprises to the production of just such equipment, for example, by acquiring licenses for the production of the required equipment. Given that domestic equipment is 3-4 times cheaper than imported, the transfer of the coal industry to domestic equipment will help increase its profitability. In addition, this will create thousands of new jobs in the regions of Siberia.

The problem of the impact of coal mining on the environment is not just hushed up, it remains poorly understood. The territory of the Kuznetsk Basin, where the coal basin of the same name is located, according to ecologists, is the most neglected area. Meanwhile, the largest cities of the region are concentrated in it - Novokuznetsk, Kemerovo, Prokopyevsk, Belovo, Leninsk-Kuznetsky, Tashtagol, Kiselevsk. Practiced methods of coal mining and processing in the territory of the Kuznetsk coal basin, whose capacity is estimated at 500 billion tons, have led to a significant transformation of the environment. Transformation is associated with catastrophic disturbances, when, as a result of anthropogenic impact, the natural landscape, soil cover and, along with it, flora and fauna are completely destroyed (due to the formation of quarries and dumps). Plowing of land, logging, fires, construction of access roads, roads, damages the structure of phytocenoses. As a result, not a single river within the Kuznetsk Basin is suitable for drinking, although the water descends from the mountains is ecologically clean. The situation is aggravated by the fact that the Kuznetsk Basin is surrounded by the Shor Highlands in the south, the Kuznetsk Alatau in the east and the Salair Ridge in the west. This leads to the fact that harmful substances do not go further than the slopes of the mountains, concentrating exclusively on the territory of Kuzbass.

Scientists see a way out of this situation in carrying out large-scale measures for the rehabilitation of disturbed territories, which must begin after the completion of the development of a coal mine or mine. The complex of these measures includes the restoration of land fertility, the cleaning of rivers, the creation of forest parks, protective forest belts and recreation areas. Specially protected territories should appear to preserve the biodiversity of the environment. The task is to embed mining enterprises into the cultivated landscape and thereby preserve the biological diversity of the region's nature.

3. Physiological mechanisms damaging organs

Of the professional factors of coal production, the existence of which, their influence on the body and measures to prevent the health problems they cause, every miner should be aware of, first of all, dust. Along with the impact of coal dust on the respiratory system, it also affects other organs and body systems. So, coal dust contributes to the occurrence of pustular diseases of the skin of the subcutaneous tissue (boils, panaritiums, abscesses). When dust is swallowed, the digestive tract can also suffer. Dust, irritating the mucous membrane of the eyes, contributes to the development of conjunctivitis, trauma to the cornea of ​​​​the eye.

However, it should be noted that the effect of mixed dusts on the respiratory system has not been sufficiently studied. There is no substantiation of the possibility of using cytochemical indicators for express assessment of the degree of dust cytotoxicity in alveolar macrophages, as well as for assessing the health status of workers in industrial enterprises and the risk of occupational disease. In this regard, the cytochemical characterization of neutrophils and erythrocytes of peripheral blood is of particular interest. It is known that peripheral blood obtained from a finger is convenient for a wide and multidisciplinary study, and its indicators provide enough information to judge metabolic changes in the respiratory organs.

Working underground is associated with significant physical exertion, which, combined with an elevated temperature of the working environment, causes a sharp increase in sweating (up to 4 l/day), leading to a deficiency of water-soluble vitamins and minerals.

Energy costs for miners, depending on their professional affiliation and the nature of the work performed, can fluctuate in a wide range of 14,640-20,900 kJ (3500-5000 kcal). The daily ration should contain 110-190 g of proteins, 120-180 g of fats, 480-620 g of carbohydrates. If the daily energy consumption is less than 16,700 kJ (4000 kcal), the ratio between proteins, fats and carbohydrates should correspond to the ratio of 14:30:56, and with a higher energy consumption - 14:35:51.

Probability of occurrence silicosis reduce methionine and cysteine. Therefore, it is necessary to include sources of milk proteins (cheeses), poultry, fish, legumes, etc. in the menu of workers working under the influence of silicon compounds.

The change in the nature of the clinical course of the disease is largely associated with impaired immune reactivity and lipid metabolism.

Therefore, it seems appropriate to trace the early immunological and metabolic changes during inhalation of UPP for timely diagnosis and preventive measures. This makes it possible to implement experimental models. In this regard, the aim of the study was a clinical and experimental study of the features of immune reactivity and lipid profile upon inhalation of UPP.

The role played by coal dust in accidents at mines is recognized as increasingly important, as noted in the work, the author of which indicated that it was first realized in Great Britain after the explosion that occurred in a coal mine in Northumberland (Wales) in 1803. However, understanding this role at that time was still imperfect. As a result of an accident in 1844 at the mines in Durham, owned by the Haswell company, 95 people died; renowned scientist Michael Faraday was invited to lead the investigation. And although the report on the accident noted that it was not firedamp (methane) that caused it, it was not until more than 50 years later that Galloway, a professor of mining at Cardiff University, determined that coal dust was mainly the cause of both this and more serious explosions. .

The mechanism of the phenomenon is currently known. It lies in the fact that a relatively weak methane explosion can cause air turbulence sufficient to form a cloud of coal dust in the adit. The ignition of the dust, in turn, generates a shock wave that raises even more coal dust, which eventually leads to a devastating explosion. The paper determined that most of the 645 similar accidents in coal mines that occurred only in Great Britain from 1835 to 1850 were caused by dust explosions. Cybulski notes that the number of accidents in coal mines worldwide with the number of victims of at least 50 was 135, or an average of 151 people, during the period from 1900 to 1951. for one accident. In accordance with the same source, due to explosions in US mines, the average number of casualties for the period from 1931 to 1955 amounted to 117 people. in year.

In order to prevent or ultimately mitigate dust explosions in coal mines, it is necessary to: a) prevent initiating explosions by venting methane and eliminating possible sources of ignition; b) to limit, if possible, the amount of dust in the adit; c) moisten coal dust; d) use an inert powder. Such an inert powder is a silicate-free dust, usually lime. The powder is loaded into a trough suspended from the ceiling of the adit, which is preferable to simply mixing it with coal dust, as was done before. When an explosion occurs, the chute swings and the inert powder is scattered, mixing with the coal dust in the air. The lime absorbs the heat released during combustion and thus the rate of flame propagation is reduced. In addition, lime participates in the reaction of endothermic decomposition, which cools the gas. On fig. 12.1 shows a diagram of the distribution by years of the number of victims from accidents in mines that occurred in the UK (accidents with at least 20 victims were taken into account). It is easy to see that the largest accidents occurred in the distant past.

Analyzing the complaints of miners, it can be noted that a high frequency of colds among miners is observed in the initial period of work underground, when the body of the worker, getting into adverse conditions, has not yet adapted to them. Then, due to the compensatory-adaptive mechanisms of the body, colds are observed less frequently, and only in persons with an experience of more than 31 years there is again a slight increase in the incidence, which is apparently associated with a decrease in the immunobiological properties of the body at the appropriate age. .

Dust and smoke as harmful impurities in the air have become objects of paramount importance in the struggle to maintain the frequency of the air environment, since their presence invariably created tangible inconveniences, and they themselves were most often the result of human activity. Dust is the smallest solid particles that can stay in suspension for some time. Dust is characterized by its chemical composition, size and shape of particles, their density, electrical, magnetic and other properties.

Damage to the mucous membrane of the respiratory tract by dust deposited on it gradually leads to chronic inflammation - “dust bronchitis”, in the development of which the microflora of the respiratory tract also plays an important role. Peribronchial sclerosis characteristic of silicosis, accompanied by bronchial deformation, as well as a change in the physical properties of mucus associated with the action of SiO2 on goblet cells, disrupt the normal transport of this mucus along with dust particles and pathogenic microorganisms, contributing to the further development of the endobronchial process. Thus, dust bronchitis is a combined infectious-dust lesion with a predominance of the role of one or another component. In addition, the development of chronic bronchitis can occur without a significant participation of exogenous irritants (due to repeated catarrhal and infectious respiratory diseases), and among the irritants that certainly contribute to this development, an important role belongs to non-professionals (primarily smoking). However, the increased prevalence of chronic bronchitis among eggs exposed to various industrial dusts is beyond doubt, and therefore in Kazakhstan this disease is officially classified as an occupational disease (“chronic dust bronchitis”). Under the influence of dust, diseases such as pneumoconiosis, eczema, dermatitis, conjunctivitis, allergies, etc. can occur. The finer the dust, the more dangerous it is for humans. Particles of 0.2 to 0.7 microns in size are considered the most dangerous for humans, which, when they enter the lungs during breathing, are retained in them and, accumulating, can cause diseases.

Modern scientific and technological progress in the coal industry has significantly influenced the sociological, physiological, psychological, production and economic aspects of the work of miners. Working conditions in coal mines are often characterized by unfavorable combinations of temperature and relative humidity of the working environment, the possibility of contamination with harmful gases, high dust formation in all technological processes, lack of daylight, difficulties in organizing hot meals, water supply and sewage underground, often forced position of the body under earth. The operation of mining machines and mechanisms in confined spaces is accompanied by noise and vibration.

4. Occupational diseases of coal miners

Occupational morbidity in the Kemerovo region. remains one of the highest in the Russian Federation, exceeding the level for the country as a whole by almost 7-8 times; professional patients.

The highest occupational morbidity is registered in Anzhero-Sudzhensk, Osinniki and Prokopyevsk.

The morbidity of miners with temporary disability is at an average level compared with the morbidity of workers in other industries. In the underground group of workers, as a rule, a higher level of morbidity is noted than in the above-ground group of workers in the same mines. When comparing the incidence of morbidity among miners of individual coal basins, one can note a significant difference both in the general level of morbidity and in its nature; here, to a certain extent, the specifics of the sanitary and hygienic conditions of work and life, which are determined by many factors (the climatic and geographical zone of the location of mines, their depth and length, the state of ventilation, water supply, the method of excavation of minerals, the quality of medical care, etc.) affect.

The miners, primarily working in longwall and preparatory faces, have a very high level of occupational injuries. In recent years, miner injury rates have been steadily declining due to the mechanization of coal mining and more careful compliance with safety regulations.

Of the nosological forms, the largest share (up to 25 - 30%) is occupied by influenza, catarrh of the upper respiratory tract, tonsillitis, etc., the so-called colds. Their appearance is facilitated by cooling the body, getting wet clothes and shoes. One of the first places in the general morbidity of miners is occupied by pustular skin diseases, which is associated with skin contamination with dust, the use of dirty overalls, microtrauma of the skin, and the use of untreated mine water for washing.

The number of acute gastrointestinal diseases and helminthiases is relatively high among miners, which is associated with the lack of properly organized underground sewage and cleaning of mine workings in a number of mines, poor drinking water supply, food intake directly at the place of work and improper diet.

Among the workers of hydraulic mines, high morbidity rates were noted for such nosological forms as diseases of the peripheral nervous system and rheumatism. The level of other nosological forms in the general structure of the morbidity of miners differs little from the morbidity rates of workers in other industries. Working conditions in mines can cause occupational diseases of miners.

Until 2005 in the structure of occupational pathology the first place was occupied by dust respiratory diseases (31.5%), occupational hearing loss was 24.4%, vibration disease - 17.2%, diseases of the joints and muscles - 20.9%. In 2005, there were changes in the nosological structure of occupational pathology. The first place is occupied by diseases of the joints, tendons and muscles (27.9%), vibration disease is 23%. Compared to 2001-2003, the share of respiratory diseases (21.2%), occupational hearing loss (17.6%) has decreased; occupational infectious diseases accounted for 1.5%.

In the structure of morbidity with temporary disability, three nosological groups prevail: diseases of the respiratory system, diseases of the musculoskeletal system, and injuries (up to 55% of all causes of temporary disability).

Analysis of the distribution of occupational diseases by industry in the Kemerovo region. showed that for 2003-2005. 77.8% of occupational patients are in coal. Basically, these are people employed in underground mining. In non-ferrous and ferrous metallurgy - 5.7% of occupational patients, in mechanical engineering, metalworking and the electrical industry - 4.7%, in construction - 2%, the share of the agro-industrial complex is 1.9%, in health care - 1.4%. This structure has essentially not changed over the past 5-6 years. Thus, it is confirmed that in the coal industry of Kuzbass the highest occupational morbidity

Of the factors of the production environment, the most significant for occupational risk are: noise, vibration, coal-rock aerosols, toxic substances (carbon monoxide, nitrogen dioxide) . The impact of noise and vibration on workers is due to the imperfection of mining equipment. So, according to the results of measurements at the coal mines of Novokuznetsk, the noise levels at the workplaces of excavator drivers exceed the MPC by 4 dB, the total vibration - by 4 dB, the local vibration levels are higher than the required values ​​- by 1-2 dB. At the workplaces of drilling rig operators, the levels of sound pressure and general vibration exceed the maximum allowable by 3 dB. In the cabs of drivers of heavy vehicles, noise levels are 2-4 dB higher than the MPC, the total vibration exceeds the MPC by 6 dB.

When managing mining and transport equipment, in addition to noise and vibration, workers are adversely affected by the severity and intensity of the labor process, which are characterized by physical overstrain of the muscles of the arms, shoulder girdle, and body, as a result of which pathology of the organs of the musculoskeletal system develops. An aggravating factor in the development of occupational diseases is a 12-hour work shift. The risk group for the development of occupational pathology includes such professions as excavator and bulldozer operators, drilling rig operators, drivers of heavy vehicles. The working conditions of these professions are characterized as harmful of the 3rd class. Dust exposure miners, metro builders, masons, workers of cement, brick, tile, flour-grinding, sugar factories, road workers, moulders, foundry workers, textile workers, workers of confectionery industries are exposed. Once in the respiratory tract, dust particles cause inflammation of the tissue of the pulmonary vesicles, which leads to the development of connective tissue in them. Broncho-pulmonary diseases of professional etiology continue to be the most important problem in medicine in terms of the amount of social damage caused, which is primarily due to insufficient knowledge of the mechanisms of action of fibrogenic dust of a mixed composition, as well as the action of combined factors of gases, aerosols, etc.

Coniotuberculosis occurs among coal workers much less frequently than among mining workers, and proceeds much more favorably.

The prevalence of pneumoconiosis among workers in the coal industry is decreasing every year. In 1963-1964 in the Donetsk basin, during annual medical examinations, less than 1% of those examined were found sick. Pneumoconiosis in miners of the Donetsk basin is detected with an average dust experience of 8-10 years.

Coal dust is evaluated from two points of view: sanitary-hygienic and safety. The sanitary and hygienic value of coal dust is determined by the changes that it causes in the respiratory system. The main place among them is occupied by pneumoconiosis. The most important role in protecting the body from the harmful effects of industrial environment factors belongs to nonspecific protection, its basal main link, namely, phagocytosis, carried out by alveolar macrophages of the lungs and blood neutrophils. In the development of protective and adaptive mechanisms that occur in the body at the early stages of the pathological process, an important role belongs to the earliest metabolic reactions occurring at the cellular and subcellular levels.

Dust explosion is an object of intensive study, which is the subject of numerous works and separate monographs. It can be considered in two distinct aspects: dust explosions in adits and dust explosions in equipment and inside buildings. The former are characterized by a shock wave propagating along the adit, the length of which can reach several kilometers. Although the description of dust explosions in coal mines does not correspond to the main topic of this work.

This reduces the respiratory capacity of the lungs and disrupts gas exchange; along with this, keratinization of the epithelium of the airways occurs, in connection with which its ability to retain dust particles decreases. Consequently, with the systematic exposure to dust, the supply of oxygen to the body through the lung tissue worsens and the barrier function of the respiratory tract decreases, occupational diseases develop, for example, silicosis, which occurs under the influence of quartz dust. It is known that prolonged exposure to any damaging factor leads to disruption of enzyme systems and metabolism carried out in cells, which are non-specific protection factors. In recent years, factual material has been accumulated, which made it possible to suggest that changes in the functional and metabolic activity of blood leukocytes can act as sensitive indicators of homeostasis disorders in the respiratory organs during early protective and adaptive reactions. According to the opinion, quantitative and qualitative changes in blood elements, namely, a decrease in the functional activity of leukocytes, an increase in the level of destruction reflect the initial phenomena of decompensation. .

The leading forms of occupational diseases are silicosis, anthracosis and dust bronchitis, vibration disease, diseases of the musculoskeletal system, neuritis of the auditory nerves and bursitis. According to the data of the Research Institute of Occupational Health and Occupational Diseases of the Academy of Medical Sciences of the USSR [Vorontsova E.I., 1984], as a result of the introduction of health-improving measures of a social, engineering, technical and therapeutic nature, the level of occupational diseases of the respiratory system is steadily decreasing. Thus, during the period from 1975 to 1980, the incidence of pneumoconiosis in the coal industry fell by more than half. The forms of pneumoconiosis depend on the nature of the coal, in particular on its strength and ash content, the percentage of silicon dioxide in coal and rocks, as well as on the length of service in mines and work on coal or rock, and the degree of dust content in the air. The predominant type of pneumoconiosis in miners is stage I anthracosilicosis. It is registered among workers with 15-20 years of underground work experience. Chronic dust bronchitis is becoming increasingly important in the occupational pathology of miners. In addition to industrial dust, factors predisposing to the development of chronic dust bronchitis are a cooling microclimate, pollution of the mine atmosphere with irritating gases, frequent acute respiratory diseases, and smoking.

Vibration disease ranks second after pneumoconiosis among occupational diseases of miners. It can be found in miners who are constantly working with jackhammers and drills. Moments that aggravate the harmful effect of vibration are muscle strain, forced working posture, cooling of the hands and the whole body, which can be observed in watery mines, especially with low temperatures of air and developed soil. Among the miners who work for a long time in conditions of intense noise (100 dB or more), there have been cases of neuritis of the auditory nerves and other symptoms of noise pathology.

Of the occupational diseases of the musculoskeletal system among miners, the leading place belongs to bursitis.

5. Sanitary and hygienic standards for coal mining

The parameters of the microclimate, the levels of physical factors (noise, vibration, ultra- and infrasound, electromagnetic fields), the content of dust and harmful substances in the air of the working area must comply with hygienic standards. The leading harmful factors in the extraction and processing of coal (oil shale), leading to the development of serious occupational diseases, are high dustiness, intense noise and vibration, high severity and intensity of labor, most pronounced in underground mining.

In all technological processes requiring the use of water for dust suppression, and for the sanitary and domestic services of workers, water is used that, in terms of bacteriological and sanitary and hygienic indicators, meets the hygienic requirements for water quality of centralized drinking water supply systems.

For the purpose of dust suppression, the use of mine and other waters for supplying water to sprinklers, foggers, drilling and loading machines is prohibited if the concentration of radon or thoron in them exceeds curie / l. If there are no other sources of water supply, then in order to use waters containing emanations in large quantities, measures are taken to de-emanate them.

The use of surface-active substances (hereinafter referred to as surfactants) in order to bind settled dust is possible only in a mechanized way. Workers who have direct contact with highly concentrated solutions of surfactants, polymeric materials, reagents and antifreezes used for heat, hydro and gas insulation, prevention of sudden outbursts and strengthening of mountain ranges, as well as means of treating coal against freezing and weathering, are provided with protective waterproof clothing and shoes, goggles, respirators, rubber gloves.

When developing technological processes and designing equipment, maximum mechanization of repair, installation and dismantling is provided, and measures are taken to reduce the levels of factors in the working environment and the labor process during the performance of these works.

Operation and repair of devices with sources of ionizing radiation, radiation monitoring and registration of its results are carried out in accordance with the requirements for ensuring radiation safety.

Requirements for the conduct of work and for the premises in which mercury-filled instruments, devices, devices are installed must comply with the provisions of sanitary rules when working with mercury.

The use and maintenance of lasers is carried out in compliance with hygienic requirements for their device and operation.

The employer provides workers with overalls, safety shoes and personal protective equipment (hereinafter referred to as PPE), washing and disinfecting preparations and organizes their proper storage, use, cleaning, washing, repair, disinfection and other types of their preventive treatment.

In the organization for the extraction and processing of coal, production control is carried out in accordance with the hygienic requirements for organizations engaged in the extraction and processing of coal (oil shale). The employer is obliged to provide information to the authorities authorized to carry out state sanitary and epidemiological supervision on the severity of factors in the working environment, the sanitary condition of the atmospheric air, water bodies, soil, solid industrial waste and the compliance of the technology used with the approved project.

In Russia, standards have been developed and put into effect for a long time in the field of various harmful factors. In many countries, there are laws and federal programs for the number of land reclamation followed by mining, technologies have been developed for filling goaf with household and construction waste. If mining regulations or safety requests are met near mining operations, undesirable consequences such as underground fires, fires in waste dumps, pollution of watersheds with waters containing acids, metals or suspended solids, and in addition landslides are possible unstable slopes. In many countries, including the United States, there is a series of laws that really cover all aspects of the development of coal deposits and provide for the implementation of continuous monitoring during mining operations, which excludes the possibility of undesirable environmental consequences. .

The presence of substances with toxic properties in dust increases its danger. The concentration of dust in real production conditions can range from a few mg/m3 to hundreds of mg/m3. GOST 12.1.005-88 "General sanitary and hygienic requirements for the air of the working area" establishes the maximum permissible concentrations (MPC) of dust in the air of the working area.

6. Means and methods of protection against a harmful factor in the workplace

Prevention and prevention measures: anti-dust measures are determined by the nature of production. In order to reduce the harmful effects of dust on workers, in case of exceeding the MPC, they limit the time of work, use personal protective equipment, use local and general ventilation, constant wet cleaning of premises.

Measures to control the formation of coal dust:

1.Humidification of coal seams (preliminary injection of water into the seam).

2.Irrigation, pneumohydraulic irrigation.

.Water curtains.

.Water-air ejectors.

.Hydrojet sprayers.

.Dust collection (dust extraction, construction of casings on overflows, fabric partitions)

.Dedusting ventilation

.Sharp cutting tool.

Coal dust explosion prevention measures:

1.Wash, moisturize.

2.Sweeping.

.Whitewashing: lime-cement mortar; 1 part cement, 2 parts lime, 30 parts water.

.Water curtains, foggers.

.Schisting.

.Shale or water barriers.

.Drinking water, or from treatment facilities.

Wellness activities. Dust reduction; heating the air supplied to the mine during the cold season; elimination of seepage and accumulation of water in the places of residence and movement of workers; installation of heated chambers in the near-shaft yards for miners waiting to be lifted; arrangement of rational household facilities with dressing rooms, showers, installations for storage, dedusting, drying, washing and repairing overalls, daily sanitation of microtraumas, washing safety shoes, ultraviolet irradiation of workers. In coal mines - the device of mobile heated rooms for heating workers in the cold season, insulation of the cabs of excavators, bulldozers and dump trucks, timely issuance of the necessary overalls and footwear.

In order to prevent occupational diseases in the coal industry, mandatory pre-employment and periodic medical examinations have been introduced. Those working in tunneling and clearing works are subject to medical examination once every 12 months, the rest of the mine workers - once every 24 months. There is a wide network of dispensaries equipped with the necessary apparatus and equipment for physiotherapy, therapeutic exercises, and diet. Recently, the so-called integrated mechanization of coal mining, based on the use of powerful coal combines, metal shields and powered supports, has been widely introduced, which will allow switching to remote control of the units.

Protecting miners from the harmful effects of dust includes:

air dedusting;

organization of ventilation of mine workings;

measures to combat the dust content of air entering the mine from the surface;

providing miners with personal protective equipment against dust (filtering respirators). An important role in the prevention of occupational dust diseases is played by a healthy lifestyle, the rejection of bad habits, sufficient sleep, rational nutrition, sports, and breathing exercises. .

CONCLUSION

The coal industry is a branch of industry for the extraction of coal from its deposits in the earth's crust. There are two methods of coal mining: closed (in mines) and open (in cuts, quarries).

The main works in the mines are: cutting the seam with the help of cutting machines, breaking coal with the help of explosives, pneumatic jackhammers, combines, "mechanized" complexes or hydraulically. From the longwalls, coal is transported by conveyors to the haulage drift and is delivered by electric locomotives to the shaft for delivery to the surface.

In the cuts, the coal seam is loosened by drilling and blasting, the coal is loaded onto dump trucks and transported to the surface.

Leading professions in underground work: tunnellers, drillers, blasters, bulk breakers, fasteners, combine harvesters and cutters. At most mines, they are combined into integrated teams with wide interchangeability. The leading professions in quarries are drillers, explosives, excavator and electric locomotive drivers, bulldozer and dump truck drivers.

Occupational hazards in the coal industry: unfavorable meteorological conditions, emission of dust (see) and harmful gases, noise (see), vibration (see), on gently dipping thin layers, a forced position of the body, in hydraulic mines, the danger of eye injuries (for hydraulic monitors).

Almost all coal mines contain methane, carbon dioxide, carbon monoxide, sulfur dioxide and nitrogen oxides.

Dust in the air of mines and cuts consists of coal and rock particles. The content of mineral substances in it ranges from 15 to 40%, free silicon dioxide - from 1 to 10%. According to the Sanitary Norms SN 245-71, the maximum allowable concentration of coal dust in the air of workings should not exceed 10 mg/m3 - if the content of free silicon dioxide in coal is up to 2% and 4 mg/m3 - if its content is more than 2%. However, the dust content of the air often exceeds this value by many times, especially when harvesters are operating. To reduce dust formation during coal mining, the following are used: 1) water injection into the coal seam before coal is extracted from it; 2) spray irrigation with water of places of the greatest dust formation; 3) dry dust collection from the places of coal breaking with special devices of a combine or "mechanized complex".

Industrial injuries are always higher among the workers of the downhole group. The most common causes are violations of safety regulations during mining operations and coal transportation.

Occupational diseases: silicosis, silicoanthracosis, anthracosilicosis; are observed in workers in rock and coal faces with an average work experience of 15-20 years. Bursitis (see) occurs in workers on gently dipping seams, vibration disease - in combine drivers working in mines with steep seams and in drillers.

Pustular skin diseases and catarrhal diseases, myositis, neuritis, radiculitis are more common among those working in cold damp slaughter, when working in an uncomfortable position and great physical exertion.

Bibliography

1. T.A. Hwang, P.A. hwang. Fundamentals of ecology. Series "Textbooks and teaching aids". - Rostov n / a: "Phoenix", 2001. - 256 p.

Belov S.V. Life safety - 1999 - 449 p.

O.E. Falova. Physiology of the respiratory system - 2006 - 124 p.

Life Safety: Textbook. Part 2 / E.A. Rezchikov, V.B. Nosov, E.P. Pyshkina, E.G. Shcherbak, N.S. Chvertkin / Edited by E.A. Rezchikov. - M.: MGIU, - 1998.

5. Golubev E.I. Cleaning work. - M: Medicine, 1998.

6. Ecology and life safety: textbook. allowance for universities / D.A. Krivoshein, L.A. Ant, N.N. Roeva and others; Ed. L.A. Ant. - M.: UNITI-DANA, 2000. - 447 p.

Works similar to - Coal dust. Physiological mechanisms of damaging effects on the body

Ordinary sawdust and wood chips can be burned in boilers made for this purpose, but not everything is so simple with coal dust.

Those who have already tried to heat their boiler with such fuel understood that half of it simply disappears, falling between the bars of the grate into the ashes, while the second half bakes into stone and prevents the burnt fuel from getting into the ashes. All these reasons lead to a decrease in the quality of combustion, and hence heat transfer.

But on the other hand, throwing out coal dust is at least stupid, it contains a large amount of energy. And here the problem can be solved by turning coal into briquettes, which we will discuss below.

More about briquetting technology

A number of parameters are used to classify fuel briquettes:

  • the material from which the briquette is made;
  • form;
  • security;
  • environmental friendliness;
  • type of packaging.

You can, of course, burn such dust, having previously melted the boiler with firewood, and already pour a fine fraction on them. But this approach is not a solution, it is very troublesome, because you need to pour dust from coal little by little, which means often.

If you put a large amount of coal dust on the firewood at once, it will still spill into the grate and thus the problem of partial combustion of fuel will not go away, besides, the rest of the dust will fall between the firewood, block the air flow and combustion will significantly weaken.

To get around all of the above inconveniences, you need to press coal dust into briquettes, which in this form will burn perfectly, giving off all their energy.

Russian developments

The solution for pressing a fine fuel fraction was invented at the beginning of the last century by the Russian researcher A.P. Veshnyakov.

His idea is still used in industry and everyday life. The essence of the idea is to press wood powder into solid elements that can burn and give off heat no worse than coal itself.

Without talking about the detailed technology and without listing their types, it can be noted that they come in two main types:

  • with the use of binding components, industrial combustion;
  • without them, for home use.

It is important to know: briquettes made using a technology that involves the use of matching elements cannot be used in everyday life. When they burn, a lot of toxic substances are released, which are removed by special equipment in production.

We are talking about the technology of making briquettes without the use of binding components. The production goes like this:

  • initially, coal dust and small pebbles are crushed, the largest particle at the exit should not be more than 6 mm;
  • the mixture is then dried to a moisture content of 15%. For this, steam and gas type dryers are used;
  • then the dust is cooled and transferred to the press. Its impact on the fine fraction occurs with a pressure of 100 to 150 MPa, in a special stamp-type press;
  • after which the finished product is stored.

The requirements for particle size and compaction pressure may vary depending on the equipment used and the purpose of the fuel. For example, the UNITEC production line works with particles up to 0.25 mm and their moisture content from 6 to 16%.

As a result, we get a product with an ash content of 15-20%, capable of withstanding a pressure of - 3 kg / cm, and when falling from a height of two meters, the weight loss from impact will be insignificant. The energy intensity of briquettes will depend directly on the coal dust from which they are made.

industrial production

For the production of industrial briquettes, the following binders are used:

  • oil-bitumen mixture;
  • cement;
  • lignosulfonate additives;
  • liquid glass;
  • molasses.

For the processing of small particles of coke and some other types of coal, cement is often used, as well as liquid glass. Such materials are mainly used in metallurgy, where the use of these substances is allowed.

Coal tar with oil bitumen is also used for the manufacture of industrial coal briquettes. It is impossible to heat residential buildings with them, since a large amount of benzopyrene and other toxic elements prohibited by the SES are released.

Home production

In order to make coal briquettes with your own hands, you need to have coal dust itself and clay, a safe binding element. By adding a little water, dust and clay are mixed 10: 1, thus, the solution acquires the desired consistency. It is very important to mix the substances thoroughly.

To create briquettes, you can use both a conventional construction mixer and special equipment, such as the Weber brand. If you decide to make briquettes by hand, you can use any containers, boxes, pans, etc. as a mold. At the end of production, fuel briquettes must be dried.

Note: the use of equipment for creating briquettes at home will be unprofitable.

Naturally, the briquettes made at home are not ideal. Their strength is not as great as that of industrial counterparts, they have different humidity and heat transfer.

But be that as it may, they burn perfectly in the boiler, much better than sintering and falling through coal dust. Yes, and the cost will certainly please them. The positive feedback left about this technology speaks for itself.

How coal briquettes are produced, see the following video:

Coal dust is generated during the following production operations:

  • 1. Breaking coal with combines and blasting.
  • 2. Hole drilling.
  • 3. Loading coal by loading machines.
  • 4. Transportation of coal by conveyors.
  • 5. Loading at loading and unloading points.

Dust is characterized by a set of properties that determine its behavior in the air, its transformation in the body, and the effect on the body. Of the various properties of coal dust, the chemical composition, solubility, dispersion, explosiveness, shape, and electrical charge are of the greatest importance.

For the assessment of dust from the hygienic side, the most important feature is the concentration of dust in the air, its dispersion and specific gravity.

Dust concentration is the weight content of suspended dust per unit volume of air. Dust concentration is sometimes also expressed as the number of dust particles per unit volume of air, and in some foreign countries this value is taken as the main indicator of dust content. However, it is not the number of dust particles that is of paramount importance, but their mass, therefore, the weight method of hygienic assessment of air dust content was adopted as the main one. The higher the concentration of dust in the air, the greater its amount during the same period settles on the skin of workers, gets on the mucous membranes and, most importantly, enters the body through the respiratory system.

Dispersion - the degree of grinding of a substance, which determines the duration of dust in the air, penetration into the respiratory tract, sorption capacity, etc. The dispersion of dust is expressed as the percentage of individual dust fractions in relation to the total number of dust particles. For a hygienic assessment of the dispersion of dust, it is conventionally customary to divide it into the following fractions: less than 2 microns, 2-4 microns, 4-6 microns, 6-8 microns, 8-10 microns and more than 10 microns.

The dispersion of coal dust in 82 - 94% is less than 5 microns, which is an unfavorable factor, because fine dust affects the deeper parts of the respiratory tract.

The hygienic value of the specific gravity of dust is reduced mainly to the rate of its settling: the higher the specific gravity of the dust, the faster it settles and the faster the self-purification of the air occurs.

Material composition. The qualitative composition of coal dust, as a rule, is determined by the composition of the coal seam, and rock dust - by the composition of host rocks and rock layers. The quantitative ratios of the dust components depend on the technological processes and the hardness of the rocks subjected to abrasion or grinding. The content of components in the dust due to their different hardness may be different than in the massif, however, due to the complexity of sampling for analysis, their composition with an accuracy acceptable for practice is assumed to be similar to the composition of the rock.

The most important of all the ingredients of the material composition, the content of which determines the harmfulness of dust to health, is first of all free, and then bound silicon dioxide.

The shape of the particles. Coal dust consists of particles of various irregular shapes - single or collected in aggregates.

The shape of the particles can be: cube-shaped, columnar, platy, elongated-platy, lamellar, elongated-lamellar.

The predominance of one form or another depends on the physical and mechanical properties of coal (structure, fracture, hardness, brittleness, etc.). For particles larger than 40 µm, the formation microfracturing has the main influence on the shape. The shape of smaller particles is determined by the physical and mechanical properties of the coal substance.

A coal particle with a diameter of 10 microns, located at a distance of 1 m from the soil, reaches it in 4 minutes, while with a diameter of 1 micron, this time is 6.7 hours. Thus, particles with a size of 1-2 microns practically do not settle.

electrical properties. Electric charge - the presence of electric charges on the particles of the dispersed phase. Dust particles dispersed in the air carry a certain electrical charge. Their electrization occurs as a result of the adsorption of ions from the gaseous medium, the friction of particles on various surfaces or on each other. Due to the existence of many electrization conditions, a dust flow always contains particles that carry positive and negative charges. According to studies, approximately 90 particles out of 100 are charged immediately after spraying. In most cases, the average positive charge of particles of a certain size is equal to the average negative charge. The individual charge of the particles increases with their size. During the destruction of rocks, this increase obeys a quadratic law. For particles of the same size and material composition, the magnitude of the charge is determined by the dielectric properties. Particles of one sign or another may predominate in the ventilation flow. Over time, the magnitude of the charge decreases, and its predominant sign may also change. A minute after spraying, negatively charged particles predominated in the floating coal dust. After 4-5 minutes, the sign of the predominant charge of coal particles changed to the opposite.

explosive properties. Coal dust can explode. The speed of propagation of the flame of its explosion changes under the influence of many factors from several tens to hundreds of meters per second, often exceeding the sound. A powerful shock wave with a pressure of up to 1 MPa propagates ahead of the flame front.

In a dust explosion, additional energy is required to create a dust cloud of explosive concentration. Under industrial conditions, such a cloud can arise either as a result of intensive release of dust into the air during a particular technological process, or as a result of the rise of deposited dust under the influence of the energy of an ignition source.

The main factors affecting the explosiveness of dust are its dispersion and concentration, the release of volatile substances, ash content and moisture content, as well as the type of ignition source and the composition of atmospheric air.

Particles up to 1000 microns in size take part in the explosion. The explosiveness of dust increases with increasing degree of its dispersion. As the distance from the source of formation, the dust becomes more explosive, as the degree of its dispersion increases.

Factors affecting the explosiveness of coal dust:

  • 1. Explosive concentration of coal dust in suspension from 16 - 96 g/m 3 to 2000 g/m 3 .
  • 2. The yield of volatile substances - 15% or more.
  • 3. The size of dust particles is up to 1 mm, the smaller it is, the more dangerous.

The ignition temperature of coal dust is 750 - 850 ° C. The speed of the blast wave is 1000 m / s. The strongest explosion at a concentration of 300 - 400 g/m 3 .

organic dust In most cases, they do not cause pneumoconiosis on their own. The cases of coniosis described in the literature, caused by certain organic dusts, with a more thorough analysis of the symptomatology, often turn out not to be coniosis, but to other forms of lung disease. Of all the types of organic dust, coal dust is the most important. Fibroses of the lungs observed in anthraco-silicoses are caused not by coal, but, as mentioned above, by the mineral dust contained in it as an impurity, which includes quartz and silicates.

The admixture of mineral particles in coal dust can be quite significant; so, in brown coals it reaches 25-30%. Distinguishing charcoal dust particles from mineral particles under a microscope is quite difficult, since large black charcoal particles cover colorless mineral particles. The opinion that pulmonary fibrosis in these cases is caused by mineral dust is confirmed by the fact that the presence of an increased amount of silica is chemically determined in the lung tissue of workers who inhaled coal dust mixed with mineral dust.

However research recent years, conducted by the Institute of Occupational Physiology (Rabvin et al.), point to the possibility of developing pulmonary fibrosis under the influence of inhalation of pure coal dust, which does not contain either quartz or silicates. These fibroses are benign.

Dust and pneumonia. The penetration of dust into the alveoli may be accompanied by the formation of inflammatory exudate in them. This exudate, in the presence of sufficiently virulent pathogenic microbes, can spread to a more or less extensive area of ​​\u200b\u200bthe lung tissue and give a clinical picture of lobar, or lobular, pneumonia. These acute dust pneumonias are possible primarily in workers engaged in grinding the so-called Thomas slag, a by-product of steel production.

The latter thanks to the great the content of phosphorus salts is a valuable artificial fertilizer. To make the slag usable, it is ground into a powder. During the period when the grinding of Thomas slag was introduced at the factories, according to foreign authors, pneumonia was often observed among workers with a severe course and a high percentage of mortality, and the death rate from pneumonia among workers engaged in grinding Thomas slag was 30-60 times higher than the rest of the population of the same age.

Considered form pneumonia refers most often to lobar. Its outcome in cases ending in recovery may be a sharp emphysema. In addition to thomas slag, pneumonia is caused by dust of manganese ore (brown iron ore) and potassium dichromate. In Russia, these pneumonias are rare.

Along with the dust lungs spores of various fungi can be introduced - mold, radiant, etc., which leads to the development of so-called pneumomycosis. The most common infection is with Aspergillus species. Flour millers, agricultural workers, workers in breweries, workers dealing with animal hair, etc. are susceptible to infection of the lungs with fungi. The disease proceeds either in the form of pneumonia or in the form of bronchitis, mostly sluggishly, with remissions, and in most cases ends in recovery.

vegetable dust lead to acute, subacute, as well as chronic lung lesions. Their mode of action has not been elucidated, and in some cases the harmful agent found in the vegetable matter of the seeds, such as certain proteins, alkaloids, or other irritating and toxic substances, is unknown; sometimes their harmful effect is due to biological pollution (bacteria, spores, mycelium) and mineral (silicium).

The properties and characteristics of coal dust include the size of dust particles. Coal dust consists of particles up to 300 microns in size with a predominance of fine fractions. Most of all in coal dust particles ranging in size from 20 to 50 microns, depending on the fineness of grinding. Dust, especially coal rich in volatiles, is prone to spontaneous combustion, which is one of the main causes of explosions in dust preparation systems. The risk of spontaneous combustion of dust is also included in the properties and characteristics of coal dust, it increases with increasing ambient temperature and in contact with hot surfaces. The most explosive is the dust containing particles less than 200 microns. To characterize the grinding properties of the fuel, the so-called laboratory relative grindability coefficient of the fuel is used. These are important properties and characteristics of coal dust. It is understood as the ratio of the specific energy consumption during grinding (in a standard laboratory mill) of the reference and test fuels. The properties and characteristics of coal dust also include the quality of the dust particles. The quality of the dust obtained in dust preparation plants is usually characterized by the fineness of grinding, determined by the sieving of the sample on sieves with different hole sizes. As a result of sifting, the rest of the dust on the indicated sieves is determined, which characterizes the fineness of grinding. According to the sieving data, the dependence of the residue on different sieves on the particle size (sieve opening size) can be built, which is called the grain characteristic of the dust. Residue values ​​on sieves 90 and 200 µm make it possible to judge the uniformity of the dust. Obviously, the more uniform the dust, the less electricity has to be spent on its preparation. The greater the difference between the residues on sieves 90 and 200 microns, the dust is more uniform in composition. Distinguish between bulk and apparent density of dust. Bulk density is understood as the ratio of the mass of dust to its total volume (the total volume, consisting of the volume of the solid phase of the particles, the pores inside the particles and the air gaps between the particles). The apparent density of dust is understood as the ratio of the mass of dust to the total volume occupied by the solid phase of dust particles and the pores inside the particles. Bulk density is used when calculating the capacity of dust bins for dust storage. Apparent density is used in the design of dust feeders, separators and cyclones. The moisture content of the finished dust affects the conditions of its ignition and the course of the combustion process. The lower the moisture content of the dust, the easier it ignites and burns faster. Usually, dust drying is carried out in such a way that its moisture content is close to the hygroscopic moisture content of the fuel (Wh - see § 2-2).



Fuel combustion processes

Combustion is a rapid combination of oxygen with combustible fuel elements (carbon, hydrogen and sulfur) and is accompanied by the release of heat and light. Oxygen is supplied to the furnace with air. Dry air consists of two elements: 21% oxygen and 79% nitrogen. Only oxygen is involved in the combustion of fuel. In order for the combustion of fuel to begin, it is necessary to bring the temperature to the ignition temperature, at which combustion occurs independently, without heat supply. The ignition temperature depends on the type of fuel and the conditions in which the combustion process takes place. The ignition temperature of fuel oil is 500-700 °, coal 500 °, anthracite 700 °, firewood 300 °. Carbon is the main constituent of any fuel; it burns either into carbon dioxide (CO2) or into carbon monoxide (CO). When a sufficient amount of air (and hence oxygen) is supplied to the furnace, the carbon combustion reaction proceeds completely. With a lack of air, the carbon combustion reaction will not proceed completely, and much less heat will be released. Due to the incomplete combustion of carbon, not carbon dioxide is obtained, but carbon monoxide. The second combustible element that is part of the fuel is hydrogen (H2). The combustion of hydrogen is also accompanied by the release of heat. From the equations of combustion of carbon as the main combustible element of any fuel, it can be seen that with incomplete combustion of carbon, i.e., when combustion occurs with a lack of air and as a result of combustion carbon monoxide (CO) is obtained instead of carbon dioxide (CO2), heat will be released three times less. This implies the conclusion that it is necessary to strive to create such conditions under which the combustion of the fuel will occur completely, that is, with a sufficient amount of air so that carbon burns into carbon dioxide (CO2). Knowing the composition of the fuel of each grade, it is possible to calculate the amount of air required for complete combustion. If we divide the amount of air actually introduced into the furnace for burning 1 kg or 1 m3 of fuel by the calculated amount of air, i.e., by the amount of air required for the same purposes, but determined as a result of calculations (theoretically), we get a number called the excess air ratio. Therefore, the excess air coefficient is the ratio of the air practically necessary for burning a unit of fuel (kg, m3) to the calculated (theoretical) amount of air. It is always necessary to strive for complete combustion of the fuel with a minimum excess air ratio.