“It has proven its open environmental policy” - Rosprirodnadzor about the zinc plant. The question hangs in the air

Zinc and its effect on environment

1. Anthropogenic sources of entry into the environment

The main source is the release of zinc into the atmosphere during high-temperature technological processes. In this way, plus losses during transportation, enrichment, and sorting, from 1995 to 2005, 700 thousand tons of zinc were dispersed throughout the world. As a result of burning coal in 1980 137.5 thousand tons entered the atmosphere, by 2000 this figure increased to 218.8 thousand tons. The zinc content in the air in the area of ​​the non-ferrous metals recycling plant is: within a radius of 300 m -0.350 mg/m 3 ; 500m - 0.285 mg/m3, 1000m - 0.148 mg/m3, 2000m - 0.52 mg/m3. Metallic zinc is oxidized by atmospheric oxygen and precipitates in the form of ZnO oxide. On average, 72 kg of zinc falls annually on 1 km2 of the Earth's surface with atmospheric precipitation - three times more than lead, and 12 times more than copper. Significant amounts of zinc enter the soil with solid waste from brown coal power plants. In the area of ​​one of the zinc smelters, within a radius of 0.8 km, the zinc content in the surface layer of soil reached 80 mg/g. Within a radius of 1 km from the zinc plant, the zinc content in the green parts of vegetables is 53-667 mg/kg, in root vegetables - 3.5-65 mg/kg, in the soil -42-40 mg/kg of dry residue.

Wastewater containing zinc is not suitable for irrigating fields. Failure to comply with hygiene standards led in Japan to an outbreak of severe disease of the musculoskeletal system among the population who consumed rice grown in irrigation fields, where irrigation water was used that was heavily contaminated with zinc sulfide and cadmium.

Sludge poses a particular danger to the oceans waste water and the wastewater itself from chemical, woodworking, textile, paper, cement production, as well as mines, mining and smelting plants, and metallurgical plants. The threshold concentration of zinc, which reduces the efficiency of wastewater treatment by 5%, is 5-10 mg/l. A serious source of zinc entering water is its leaching with hot water from galvanized water pipes up to 1.2-2.9 mg from a surface of 1 dm2 per day. Summing up all anthropogenic sources, the total volume of zinc entering the environment is 314 thousand tons per year.

. Chemical and physical properties of zinc and its compounds

Zinc (Zincum) Zn is a chemical element of the 12th (IIb) group of the Periodic table<#"603625.files/image001.gif">

9. Methods for purifying emissions produced into the atmosphere from zinc and its compounds (selected ZnO compound)

Since the selected zinc compound - zinc oxide - is a fine powder - medium-fine dust, methods for purifying gases from solid particles will be considered.

Modern gas dust removal devices can be divided into four groups:

) mechanical dust removal devices in which dust is separated under the influence of gravity, inertia or centrifugal force.

) wet or hydraulic apparatus in which solid particles are trapped in a liquid.

) porous filters on which the smallest dust particles settle.

) electric precipitators in which particles are deposited due to the ionization of gases and dust particles contained in it.

For emissions containing this zinc compound, the most suitable treatment methods to use are porous filters, because they have the highest dust collection efficiency and are suitable for this type of particles.

Filters. In dust collectors of this type, the gas flow passes through porous material of varying density and thickness, in which the bulk of the dust is retained. Cleaning from coarse dust is carried out in filters filled with coke, sand, gravel, nozzle various shapes and nature. To remove fine dust, filter material such as paper, felt or fabric of varying density is used. Paper is used to purify atmospheric air or gas with low dust content. In industrial conditions, fabric or bag filters are used. They take the form of a drum, cloth bags or pockets working in parallel.

The main indicator of a filter is its hydraulic resistance. The resistance of a clean filter is proportional to the square root of the radius of the fabric cell. The hydraulic resistance of a filter operating in laminar mode varies in proportion to the filtration speed. As the layer of dust deposited on the filter increases, its hydraulic resistance increases.

Wool and cotton were previously widely used as filter fabrics in industry. They allow you to purify gases at temperatures below 100ºС. Now they are being replaced by synthetic fibers - chemically and mechanically more resistant materials. They are less moisture-intensive (for example, wool absorbs up to 15% of moisture, and tergal only 0.4% of its own weight), do not rot and allow the processing of gases at temperatures up to 150ºC. In addition, synthetic fibers are thermoplastic, which allows them to be installed, fastened and repaired using simple thermal operations.

Filter bags from some synthetic fabrics using heat treatment are made in the form of an accordion, which significantly increases their filtering surface with the same filter dimensions. Fabrics made of glass fiber, which can withstand temperatures up to 250 0 C, began to be used. However, the fragility of such fibers limits the scope of their application.

The development of production of metal-ceramic products has opened up new prospects in dust removal. The FMK metal-ceramic filter is designed for fine purification of dusty gases and capturing valuable aerosols from waste gases of chemical industry enterprises, non-ferrous metallurgy and other industries. The filter elements, fixed in the tube sheet, are enclosed in the filter housing. They are assembled from metal-ceramic pipes. A layer of trapped dust forms on the outer surface of the filter element. To destroy and partially remove this layer, back blowing with compressed air is provided. Specific gas load 0.4-0.6 m 3 / (m 2. min). The working length of the filter element is 2 meters, its diameter is 10 cm. The dust collection efficiency is 99.99%. The temperature of the purified gas is up to 500 0 C. The hydraulic resistance of the filter is 50-90 Pa. Compressed air pressure for regeneration is 0.25-0.30 MPa. The period between blowings is 30-90 minutes, the duration of blowing is 1-2 s.

One of the industrially produced bag filters and its characteristics are presented below.

Bag filter with mechanical regeneration of bags FRM-S.

Bag filters with mechanical regeneration of bags of the FRM-S type are reliable and effective dust collecting devices designed to capture fine dust from the air and non-flammable gases.

Scope of application: in the production of building materials, woodworking, technological processes of ferrous and non-ferrous metallurgy, etc.

The filter element of bag filters is a sleeve made of a special material, which is selected based on the operating conditions of the Customer’s installations. Regeneration is carried out by shaking the sleeves using an electromechanical vibrator.

Design and principle of operation:

The principle of operation of the filter is based on the capture of dust by a filter cloth as dust-laden air passes through it. As the thickness of the dust layer on the surface of the hoses increases, the resistance to air movement increases and decreases throughput filter, to avoid which, regeneration of dusty hoses is provided using electromechanical vibrators.

Dusty air enters the filter (Fig. 1) through the air duct through the inlet pipe (1) into the dusty air chamber (2), passes through the sleeves (3), while dust particles are retained on their outer surface, and the purified air enters the clean air chamber. air (4) and through the outlet pipe (5) is removed from the filter.

Regeneration of dusty hoses is carried out by turning on an electromechanical vibrator (6) for a short time, mounted on a mounting frame (7) mounted on vibration isolators (8).

Dust shaken off the hoses falls into the hopper (9) and is removed from the filter by the sluice feeder (10).

Specifications

Reducing the technogenic impact of zinc production on the environment is of fundamental importance for JSC “ChECP”, because Russia's largest zinc producer, located inside the city of Chelyabinsk. The sanitary protection zone established by the city authorities does not exceed 1 km.

Taking into account the above, the enterprise is constantly working to introduce environmentally friendly technologies, reduce emissions into the atmosphere, discharges into water bodies and utilize the generated solid waste in the production cycle.

Despite an increase in production volume by 10-15%, emissions of harmful substances into the atmosphere have practically not increased in recent years, and the discharge of man-made products even decreased by 10%.

The main sources of formation of technological waste gases are roasting kilns, Waelz kilns, and drying drums.

All combustion gases from the KS furnaces are sent to the sulfuric acid shop for disposal. At the same time, they are cleaned from dust, selenium, mercury and other impurities in electric precipitators and washing towers. After sulfur dioxide is extracted from purified gases in the sulfuric acid plant, they are released into the atmosphere.

The introduction of a set of measures, the main one of which is the double contact system, made it possible to ensure permissible maximum permissible limits, and the content of sulfur dioxide does not exceed 0.05%.

The problem of sulfuric acid mist emissions, the so-called tailings, was solved by installing electric precipitators EVMTR - 1 - 2.7 - 36 after the multihydrate absorber of the 2nd stage. The implementation was carried out jointly with the Gintsvetmet Institute and the Uraltsvetmetgazoochistka trust. The concentration of sulfuric acid fog decreased by 1.6 times.

Currently, further modernization of sulfuric acid production is underway, due to which the content of sulfuric acid mist is reduced by 6-9 times, and the unit capacity of the system increases by 1.8 times.

The problem with the disposal of mercury-selenium sludge has been resolved. The introduction of a new method for processing sludge made it possible to extract mercury from it under the conditions of existing mercury production facilities.

In zinc production, the main source of air pollution is the oxide process. The Waelz workshop accounts for up to two thirds of total volume gross emissions, the main ones being sulfur dioxide, zinc - lead-containing dust. During the processing of Waelz oxide, the main source of lead emission into the atmosphere is located in the lead cake drying area.

Therefore the solution environmental problems At this stage, the process was carried out in two directions:

technology modernization;

technical re-equipment.

The introduction of fluxing additives for Waelz coating makes it possible to reduce the content of sulfur dioxide in the exhaust gases of Waelz kilns from 1.5-2.5 g/Nm3 to 1-1.2 g/Nm3.

A search was carried out for new filter materials to capture dust from Waelz gases. The use of filter bags made of Nomex fabric from BWF allows you to increase the degree of capture by an additional 30%.

Modernization of gas cleaning equipment in the Waelz workshop with the installation of bag filters with pulsed regeneration of filter fabric will reduce the dust content of exhaust gases to the maximum permissible concentration (5 mg/nm3).

Another possible source of dust emissions at this processing stage is the process of drying cakes in drying drums.

A search carried out by factory specialists followed by testing of more advanced equipment showed that it is possible to eliminate drying and obtain cakes with the required moisture content (less than 20%) by introducing vertical filter presses from Larox (Finland). The design of these filters allows not only deep dewatering, but also washing of cakes.

The latter is important for the Waelz redistribution, because makes it possible to further reduce sulfur dioxide emissions by 60-70%.

At JSC "ChECZ" water is used for condensation of water vapor when cooling the electrolyte in a vacuum evaporation unit, for cooling vacuum pumps in the filter-drying department, for cooling the clinker of Waelz kilns, for washing Waelz oxides from chlorine, in the evaporative cooling system of the roasting shop and for other purposes.

As mentioned above, despite the increase in zinc production, the volume of water consumption and its discharge was reduced by 10%. The reduction in the volume of wastewater discharge is associated both with a steady increase in technological discipline and, first of all, with the development of a number of technical innovations at the enterprise. The organization of general plant recycling water supply, as well as local water supply in the main workshops of the enterprise, made it possible to ensure a water circulation rate of 95.6%.

The use of condensate from heating the leaching shop solutions for washing Waelz oxide was introduced, which made it possible to use both the condensate itself and its heat, and also increases the degree of water circulation.

The enterprise has also introduced the use of recycled water, which can be conditionally called the first category (cooling vacuum pumps, compressors, etc.), to feed the recycling system of category II (quenching and hydraulic transport of clinker, wet gas cleaning, etc.)

When recycled water is used repeatedly, impurities accumulate in it (especially zinc sulfate). In addition, when washing Waelz oxide from chlorine and regenerating filters at a water softening station, difficult-to-dispose wastewater containing sodium chlorides is formed.

Therefore, it is necessary to purify part of the circulating water and wastewater by reducing impurities to an acceptable level.

Primary purification is carried out at the plant’s treatment facilities, using slaked lime as the main reagent. The resulting sludge containing zinc, cadmium and others heavy metals, which are disposed of in the pyrometallurgical sections of the enterprise. JSC CHECP has developed and implemented technologies that allow the disposal of household wastewater (volume of about 1000 m3/day) at its own treatment facilities.

During the technological process of processing raw materials at the enterprise, the following solid waste and industrial products are generated: lead and copper cakes; copper clinker; sludge from treatment facilities and sulfuric acid production (mercury-selenium), as well as spent contact mass (vanadium catalyst) and used filter fabric.

The plant has had a regulation on waste storage and disposal since 1996. Sludge disposal was discussed above.

Copper cakes and copper clinker are completely recycled in copper smelters Chelyabinsk region. At the lead enterprises of Kazakhstan there is a demand for lead cakes of JSC CHECP. However, given that there is practically no lead production in Russia, the plant’s specialists, together with the Gintsvetmet Institute, have developed a waste-free technology for their processing.

The main object technical re-equipment The enterprise is a zinc electrolysis complex (ZEC), the construction of which is carried out according to the design of the Snamprogetti company (Italy).

The commissioning of the CEC has a significant impact on the environmental performance of the enterprise:

by converting vacuum - evaporative cooling of the electrolyte to cooling in cooling towers, water consumption is reduced by 750 m3/day, and gross emissions by 110 t/year;

the commissioning of a new zinc electrolysis and smelting department with installations for the preparation of zinc dust and dross processing reduces dust emissions by 81 t/year (including zinc sulfate - 30 t/g, zinc oxide - 11 t/g), sulfuric acid - 7 t/g , ammonia - 12 t/g, hydrogen chloride - 4 t/g.

hydrometallurgical zinc roasting dust and gas collecting

The ruins of the Electrozinc electrolysis workshop after the fire. Photo: Farniev Konstantin

It is no secret that emissions from factories and industrial enterprises are one of the main sources of air pollution, and wastewater discharges from them cause significant harm to the hydrosphere. However, when the work of one plant threatens the life and health of 300 thousand people, it is dangerous to remain indifferent.

"Electrozinc" is the largest industrial enterprise Republic of North Ossetia, occupying 70.2 hectares in the north-eastern part of the regional capital, Vladikavkaz, and one of the leading non-ferrous metallurgy enterprises in Russia, which has been producing and selling zinc, cadmium and sulfuric acid since 1904.

And “Electrozinc” is an air polluter, whose activities have caused acute discontent among Vladikavkaz residents for at least 9 years. Local residents still remember October 5, 2009, when a thick veil formed as a result of an industrial release of sulfur oxide at a plant above Vladikavkaz. Townspeople began to complain of severe headaches and sore throats. On the day of the accident, more than 500 people gathered for a spontaneous rally demanding a referendum on stopping the operation of the enterprise. By the end of the month, five more emergency emissions above the limit occurred at the plant. Since then, rallies for the closure of Electrozinc have been held regularly. Although the first protests against the work of the enterprise began back in 2003: soon after the Ural Mining and Metallurgical Company (UMMC) became its owner, local residents began to complain about harmful emissions into the atmosphere.

It should be added that the sanitary protection zone around the plant is only 300 meters - it is at this distance that residential development begins (by law, enterprises of the first hazard class, which is Electrozinc, must be at least 1000 meters away from residential areas) . Although the “zone of influence” of the enterprise is far from limited to one kilometer, but extends to almost the entire Vladikavkaz.

The storage areas for production waste are also a serious problem: huge mounds located within the city are open to wind and rain.

The head of the Russian Ministry of Natural Resources, Dmitry Kobylkin, reported on November 7 that the Electrozinc plant complied with all environmental requirements. “According to our line of Rosprirodnadzor, there have never been any comments against him. He always fulfilled everything we asked and demanded,” the minister said.

This confirms fears that it will not be possible to close the plant and rehabilitate the surrounding areas or at least reduce its emissions to acceptable levels in the near future. Scientist and public figure Tamerlan Kambolov created a petition on the website Change.org addressed to the president Russian Federation with a request to immediately and permanently close Electrozinc. To date, the petition has been signed by more than 26 thousand people.

Zinc passions do not subside
Both branches of the city government - legislative and executive - united in an effort to prevent the construction of a zinc plant in Orsk. For now, they are firmly holding the wall and do not intend to retreat. Although last week a representative of the Ural center arrived in the city again with a business proposal.
The story stretches back to last year, when Orchan residents were shocked by the news that the Russian Copper Company was going to build a zinc plant within the city. But even today, as it turned out, passions do not subside. The plant, according to the Urals residents, is conveniently located right in locality: no need to delay communications. In addition, in the Novoorsky district there is a mine that will supply copper and zinc concentrates. From the point of view of production workers, all arguments are for the construction of a zinc plant in Orsk. But the authorities do not agree.
The bright prospects for export production are not encouraging; many are wondering whether another enterprise is needed in the industrial hub of the region. Residents of the eastern Orenburg region are already suffocating from emissions from ferrous and non-ferrous metallurgy factories. In addition, the content of some maximum permissible concentrations of harmful substances in the atmosphere is exceeded. The management of the Russian Copper Company is encouraging that it will spend $20 million on environmental protection measures, and even promised to achieve 100 percent environmental safety project. But is it worth giving in to promises?

Red dust of Vladikavkaz
On November 25, 2005, residents of Vladikavkaz watched as a huge red cloud rose into the air from the territory of the Electrozinc plant. And a few minutes later the houses, roads, trees - everything was covered with dust. Residents industrial zone the North Ossetian capital were concerned about what had happened and began to call the environmental protection department at the plant. However, they were told that a breakdown had occurred in one of the workshops and it was being promptly fixed. They also assured Vladikavkaz residents of safety: the dust will not pose any threat to health and, thanks to windy weather, will go towards the Kartsinsky highway. She didn't leave. Last year, the magazine “Ecology of Production” published a note where residents of Vladikavkaz complain about “Electrozinc” and contact various authorities. The release of red dust confirms their words; technological failures and accidents often occur at the plant. The magazine's correspondents interviewed residents and here are the answers they received. “We are already suffocating from the emissions from this enterprise,” said Khasan Goliev, a bus driver, “children are born with defects, and there are more cancer patients. We dream of selling the apartment and moving to the village - the air there is clean.” According to the mother of many children, Elvira Tebloeva, as soon as the enterprise’s workshops began working at full capacity, the residents immediately became unbearable; they were constantly getting sick. There are no free beds in the Republican Oncology Hospital.
But still, the plant management denies the fact of environmental pollution. The dust emission is confirmed, but city residents are assured of its accidental origin: supposedly, a transition from one furnace to another was carried out in the firing shop. “The air currents carried away the dust particles, and there can be no negative consequences for the environment,” they believe at Electrozinc. Moreover, the residents of nearby houses suffer the most - they sound the alarm, but no one listens. The plant produces about 100 thousand tons of products per year, and paying the metallurgical giant a fine is a piece of cake. Therefore, with a clear conscience, the plant continues to pollute the environment.

Chelyabinsk residents inhale sulfur
OJSC Chelyabinsk Zinc Plant produces up to 150 thousand tons of products per year. The most powerful enterprise was built in the 50s. And not in some sparsely populated area, but right in the city center. And although the radius of the sanitary zone is 1 kilometer, people and nature were negatively affected by the plant. For fifty years in a row, the air, soil and water have been polluted. Every year, 4 tons of lead entered the atmosphere, and 44 thousand tons of solid components. Environmentalists believe that the most dangerous thing at the plant is sulfuric acid production. Content harmful gases in the air significantly exceeds the norm. 4 thousand tons of sulfur entered the city atmosphere.
There is a problem with the disposal of mercury-selenium sludge. Now it is exported to Kyrgyzstan for processing. The Miass River was subjected to barbaric pollution. Zinc sulfate, zinc oxide and ammonia were discharged into the water. In 2002, environmental issues became a priority at the Chelyabinsk Zinc Plant. Over the past two decades, CZP has undergone a full-scale reconstruction of associated and auxiliary production. An imported filter was purchased to prevent the release of lead and solid waste into the environment. An installation for recycling mercury from gases will be able to dramatically reduce emissions - up to 1.5 thousand tons. The issue with sulfuric acid has been resolved. The Eurochem company is ready to purchase acid with a fixed annual volume and price over the next five years. CZP General Director Vsevolod Geykhman has repeatedly asked the authorities to build a fertilizer production plant in Chelyabinsk. He could completely solve the problem of marketing sulfuric acid. But the public is unlikely to allow another hazardous production facility to be built in Chelyabinsk. Specialists have developed a unique project for processing facilities for the disposal of lead cakes. Moreover, this will be the only production in Russia that will be able to extract from raw materials not only lead, but also an alloy of gold and silver. The launch of the new complex will lead to a reduction in the amount of emissions in Miass by 81 tons. CZP spent about $160 million on modernization and environmental protection measures.

Tatyana Alova

The Ministry of Ecology organized a press tour to the Chelyabinsk Zinc Plant in order to check the implementation of activities that were included in the regional action plan for the Year of Ecology. " Chelyabinsk is one of the cities with a high air pollution index. Within the city there is a whole cluster of large metallurgical enterprises that make a large contribution to the formation of air pollution in Chelyabinsk. Their implementation of environmental protection measures aimed at reducing emissions into the atmosphere is one of the most important points in the implementation of the plan for the Year of Ecology"- said the Minister of Ecology of the Chelyabinsk region Irina Gladkova.

The company annually increases production volumes. According to the General Director of PJSC CZP Pavel Izbrecht, in 2016 the plant produced 174.8 thousand tons of commercial zinc, in 2017 - 183, in 2019 it plans to smelt 200 thousand tons of zinc. The growth in production volumes occurs simultaneously with the modernization of production and the introduction of “clean” technologies.

In 2009 - 2012, the company re-equipped the sulfuric acid workshop, installed filters and gas analysis equipment. Data on emissions are sent online to the City Ecological Center website. Head of the Environmental Department of PJSC Chelyabinsk Zinc Plant Irina Zolina said that in 2016 total volume emissions amounted to 4,173 tons, in 2017 the planned volume of emissions is 3,950 tons. At the same time, the permitted emissions standard for PJSC CZP is set at 12 thousand tons.

In the Year of Ecology, CZP carried out routine repairs of bag filters in the Waelz workshop, as well as routine repairs of flue ducts of contact devices and electric precipitators; washing towers in the sulfuric acid shop, which will better capture dangerous compounds such as sulfur dioxide, nitrogen dioxide, mercury, carbon monoxide and suspended solids.

During the press tour, journalists were shown a recycling water supply station. The station was launched in 2014. Industrial wastewater from the sulfuric acid department enters here; after purification, the water is returned back to process. The volume of treated wastewater is more than 3 thousand cubic meters per day. IN next year The company plans to begin construction of local treatment facilities, which should reduce the discharge of industrial wastewater into the Miass River by 500 m3/day. Construction of the facility will be completed by 2020.

The problem of recycling solid municipal waste generated at the enterprise does not go unnoticed. PJSC CZP entered into an agreement with enterprises that process secondary resources. If in 2016 the zinc plant transported 7 thousand tons of municipal waste to the Chelyabinsk city landfill, in 2017 this figure will be 1 thousand tons.

According to general director PJSC "Chelyabinsk Zinc Plant" Pavel Izbrecht In the Year of Ecology, about 480 million rubles will be spent on environmental measures, and next year - another 400 million rubles.