Recently, the environmental protection organization compiled the "discharge permit application and issuance of technical specification of non-ferrous metals industry (draft)", the "draft" standard mercury, cobalt, aluminum, magnesium, nickel, titanium, antimony, copper, tin, lead and zinc 11 kinds of commonly used non-ferrous metal smelting industry technical specification, each book (including lead and zinc as a book, a total of 10 copies).
According to national economic statistics, China's non-ferrous metal industry involves a total of 64 kinds of metals, including heavy metals, light metals, precious metals, semi-metals and rare metals five categories.Up to now, China has issued and implemented 11 pollutant emission standards for the non-ferrous metal industry, including 9 industrial pollutant emission standards and 2 comprehensive atmospheric and water emission standards.
Production status of nonferrous metal smelting industry in China
Non-ferrous metals are 64 metals other than ferrous metals (alloys of iron, manganese, chromium, and iron).At present, China's industrial production mainly includes lead, zinc, copper, aluminum, tin, antimony, mercury, magnesium, titanium, nickel, cobalt and so on.
According to the statistical yearbook of China nonferrous metals industry association, nonferrous metals accounted for more than 95 percent of the total output of the industry in 2016, including 74 percent of the total output of aluminum, 11 percent of copper and 7 percent of lead.
The total output of China's top ten non-ferrous metals increased year by year from 2010 to 2014, reaching 187.1 million tons by 2014, of which copper, aluminum, lead and zinc accounted for 96.07%.
In 2016, there were 1,156 non-ferrous metal smelting enterprises, among which 733 issued license in 2017 (218 copper, 365 lead and zinc, and 150 electrolytic aluminum), mainly distributed in hunan, guangdong, henan, shandong, yunnan, shaanxi, shanxi, ningxia, guizhou, Inner Mongolia and other regions.
Status of pollutant emission in nonferrous metal smelting industry
Non - ferrous metal industry complex, various processes, pollution factors.In recent years, the emission of pollutants per unit product of non-ferrous metals has shown a downward trend, but the output of heavy non-ferrous metals has increased rapidly, and the total emission of pollutants is still large.
The discharge of heavy metal pollutants in the non-ferrous metal industry is mainly concentrated in the smelting process of copper, lead and zinc. According to statistics, in 2012, the discharge of SO2 in the production process of major heavy non-ferrous metals (copper, lead and zinc) in China was 400,000 tons.Heavy metals (lead, cadmium, arsenic, mercury) were discharged 974 tons.
From the perspective of heavy metal pollution, the emission of lead is 680 tons, cadmium is 57 tons, arsenic is 232 tons and mercury is 4 tons.From the perspective of metal varieties, copper smelting emits 412 tons of heavy metals, lead smelting emits 566 tons of heavy metals, and zinc smelting emits 89 tons of heavy metals.
In recent years, due to long-term cumulative emissions involved in heavy metal pollution problems start showing, major river basin and regional level on heavy metal pollution events have occurred, to our country social economy sustainable development and constitutes a serious threat to people health, at the same time for the security of the ecological system in our country is a major hidden danger and insecurity.
In 2016, heavy metal emissions from non-ferrous metal smelting and rolling processing accounted for more than 50%, and atmospheric pollutant emissions accounted for more than 95%.
According to statistics, over the past ten years, the emissions of four national pollutants, emissions of smoke and dust and the contribution of various pollutant industries in the non-ferrous metal industry have been on the rise. In 2013, the contribution of SO2 and NOx emission industries in the non-ferrous metal industry accounted for about 7%.Heavy metal emissions accounted for between 30% and 90%, of which cadmium contributed the most to about 90%.
Status of air pollutant control in copper smelting industry
Among them, the pollutant emission standards for copper, cobalt and nickel industry implemented by copper smelting enterprises (GB25467) and the feasible technical guidelines for the prevention and control of copper smelting pollutants (trial) are the important basis for the implementation of pollution control technology in the production process of China's copper smelting industry.
Current situation and trend of organizational governance
Pollution prevention and control of the copper smelting technology guidelines (trial) ", "pollution prevention and control of nickel smelting technology guidelines (try out)" and "pollution prevention and control of cobalt smelting technology guidelines (try out)" (environmental protection department announcement no. 24, 2015), copper, nickel and cobalt smelting industry in China is the production process to implement the important basis of pollution control technology.Among them, cobalt smelting process is basically no fire process at present, all use wet process, so cobalt smelting production process does not emit particulate matter, sulfur dioxide, nitrogen oxide and other pollution factors, generally from the boiler emissions.
At present, the treatment technology of particles in copper and nickel smelting mainly includes electric dust collection technology, bag dust collection technology and cyclone dust collection technology.Among them, the electric dust collecting technology in cu-ni smelter is mainly used for collecting dust in melting furnace, blowing furnace, depleted electric furnace and dry flue gas.Bag-type dust collection technology is applicable to concentrate drying in copper and nickel smelting enterprises, dust collection in anode furnace of copper smelting and dust purification in sanitary ventilation system.Cyclone dust collector can only be used as primary dust collector to reduce the load of subsequent dust collector.
Sulfur dioxide pollution treatment facilities in copper and nickel smelting enterprises generally adopt ammonia desulfurization, lime/limestone - gypsum desulfurization, sodium alkali desulfurization, metal oxide absorption desulfurization, organic solution recycling absorption desulfurization, active coke adsorption desulfurization and other technologies to ensure standard emissions.
Among them, ammonia desulphurization technology is suitable for desulphurization of low concentration SO2 flue gas, especially for smelting enterprises with sufficient supply of liquid ammonia and certain demand for by-products.Lime/limestone - gypsum desulphurization technology has strong adaptability, which can partly remove SO3, heavy metal ions, fluoride ions and chlorine ions in the flue gas while meeting the requirements of low concentration SO2 treatment in copper smelting enterprises. However, it is not suitable for smelting enterprises with limited desulfurizer resources and limited site.
Metal oxide absorption desulphurization technology is suitable for desulphurization of flue gas in smelters where metal oxides are readily available or metal oxides are by-products.Organic solution recycling absorption desulfurization is suitable for low-pressure steam easy to obtain in the plant, flue gas SO2 concentration is high, the fluctuation is large, the by-product SO2 can be recycled smelting enterprises.The active coke adsorption desulfurization method is suitable for smelters with sufficient steam supply, abundant site and recyclable by-product SO2.
In addition, the majority of enterprises in copper-nickel smelting industry do not exceed the standard of nitrogen oxides, and some enterprises that cannot meet the standard stably adopt ammonia denitrification technology to meet the emission standard limit requirements.
The unorganized discharge nodes of cu-ni-co smelting enterprises mainly include the dust generated in the process of raw material handling, material preparation, transportation, drying and feeding, the smoke leakage from the inlet, outlet, slag outlet and chute of various furnaces, and the acid fog escaping from the tank in the electrolysis workshop.Therefore, the unorganized emission control measures of copper-nickel-cobalt smelters mainly include the following three points:
First, the main transportation road surface in the factory shall be hardened, and the transportation route shall be frequently sprinkled with water to remove dust and prevent dust, so as to reduce dust pollution.
Secondly, the storage and transportation of raw and auxiliary materials should adopt airtight measures and set up gas collection and dust collection facilities.Air collecting and dust collecting facilities should be set up at feeding port and dropping point during material preparation and transfer.
Third, facilities for collecting gas and removing dust and desulfurization should be set up at the entrance and exit of melting furnace, blowing furnace and refining furnace and chute.The leaching tank, purification tank and other wet process facilities should be equipped with gas collection facilities, and the acid fog purification facilities.