Harmless recycling treatment method for solid hazardous waste
Technical Field
The process relates to a method for treating hazardous solid waste into harmless resources, in particular to a method for treating low-grade lead-zinc-containing waste residues and copper-containing sludge, and especially waste residues produced by zinc hydrometallurgy.
Background
In China, most zinc smelting adopts a wet zinc smelting process, which is commonly a conventional method, a peracid leaching method, a direct leaching method and the like, but no matter which process is adopted, a considerable amount of low-grade lead-zinc waste residues and copper-containing sludge are finally produced. The slag particles are fine and contain a certain amount of zinc, lead, copper, indium, gold, silver and other associated valuable elements, and if the slag is not effectively utilized, serious environmental pollution and resource waste can be caused. In order to comprehensively utilize the slag, reduce environmental pollution, fully and effectively utilize secondary resources, obtain economic and environmental benefits, realize sustainable development of environment, resources and society, scholars at home and abroad make a large amount of research and provide a series of methods. These methods can be classified into wet process and fire process in terms of process types. However, both processes have the problems of secondary pollution and high treatment cost.
Along with the progress of society, the demand for resources is continuously increased, the global mineral resources are gradually exhausted, the improvement of the recycling of renewable resources is particularly important, the equipment level is continuously improved, and the development of advanced recycling technology is the key point.
Disclosure of Invention
Aiming at the problems, the invention provides a harmless recycling treatment method for solid hazardous waste, which is suitable for large-scale industrial production, has the advantages of multiple applicable slag types, investment saving, high efficiency, energy saving, environmental protection and low production cost.
The invention adopts the technical scheme that the harmless recycling treatment method of the solid hazardous waste is characterized by comprising the following steps: the smelting process is carried out in an oxygen-enriched side-blown furnace, the smelting process is completed in two stages, the first stage is a melting, desulfurizing and slagging stage, prepared waste slag, flux and coal particles are continuously added into the oxygen-enriched side-blown furnace, oxygen-enriched air is blown from a tuyere at the lower part of the furnace, furnace burden is melted and oxidized in the furnace, and high-temperature slag and flue gas containing sulfur dioxide are produced; the second stage is a reduction smelting stage, wherein coal and oxygen-enriched air are used for reaction, lead and zinc in the high-temperature slag generated in the first stage are reduced, so that a small part of copper and lead in the slag form lead copper matte or black copper, and the lead copper matte or black copper is deposited on the bottom of the furnace and discharged at regular time.
Further, when the two stages are performed in a single oxygen-rich side-blown furnace, the first and second stages are switched by controlling the oxygen-coal ratio.
Further, when the two stages are respectively carried out in the two oxygen-enriched side-blown furnaces, the high-temperature slag produced in the first stage is placed into the second stage through the chute to be reduced, or the high-temperature slag produced in the first stage is placed into the fuming furnace through the chute to be reduced and volatilized, so that continuous production can be realized, lead-zinc oxide smoke dust is produced, and the slag is harmlessly depleted.
Furthermore, the flue gas produced by the oxygen-enriched side-blown converter is subjected to desulfurization and denitrification and then is discharged after reaching the standard.
Further, the first-stage desulfurization smelting control conditions are as follows: controlling the water content of the furnace charge to be less than or equal to 12 percent, the feeding amount to be 10-50t/H, the coal granularity to be 5-20mm, the oxygen-enriched concentration to be 60-90 percent of industrial pure oxygen, and the smelting temperature to be 1050 ℃ and 1250 ℃.
Further, the second stage reduction stage control conditions are as follows: the particle size of the reduced coal (coke) is 5-20mm, the oxygen-enriched concentration is 30-70%, the smelting temperature is 1100-.
Further, the coal is single coal (coke) particles.
Furthermore, the flue gas produced in the furnace is subjected to waste heat recovery by a waste heat boiler, after bag type dust removal, the flue gas is washed by a desulfurizing tower and then is emptied, and the lead-zinc-containing smoke dust is conveyed to a lead-zinc system to be generated.
Further, the flux is limestone or silica.
The oxygen-enriched side-blowing technology is adopted to treat low-grade lead-zinc-containing waste residues and copper-containing sludge, so that the problem of serious environmental pollution caused by the fact that a large amount of sludge cannot be treated in the conventional stockpiling process can be solved. The produced lead-zinc-containing smoke dust can be returned to a lead-zinc system for recovery production after being recovered, so that circular economy is formed; the produced high-concentration sulfur dioxide can adopt a standard acid making process to produce sulfuric acid, the environmental pollution caused by low-concentration sulfur dioxide can be effectively solved, the produced slag forms a vitreous body, and has no components which are soluble in water and influence the environment, so that the produced slag becomes common solid waste, and waste residues can be comprehensively utilized to form a product. The invention is suitable for large-scale industrial production, and has the characteristics of multiple applicable slag types, investment saving, high efficiency, energy saving, environmental protection, low production cost and the like.
Detailed Description
The present invention is further illustrated by the following examples.
The scheme of the invention is carried out in an oxygen-enriched side-blown furnace, one furnace can be adopted for segmented production when the treatment capacity is small, and two side-blown furnaces or a side-blown furnace and a fuming furnace are adopted for continuous production when the treatment capacity is large.
The first embodiment is as follows: adopting desulfurization slagging smelting:
a process for reclaiming the dangerous solid waste without pollution includes drying the waste dregs to 12%, dewatering, automatically metering dregs, lime stone and granular coal, and continuously feeding them into side-blowing furnace while blowing oxygen-enriched air into the slag layer through the side air port at a position 0.5m lower than the surface of static molten pool. Controlling conditions according to the size of the side-blown converter: the feeding amount is 10-50t/H, the coal granularity is 5-20mm, the oxygen-enriched concentration is 60-90 percent to industrial pure oxygen, the smelting temperature is 1050 ℃ and 1250 ℃, the slag melt is ensured to be strongly stirred, so that the furnace charge particles are rapidly and uniformly distributed in the melt, the waste slag is rapidly melted, the sulfate is rapidly decomposed, and the chemical reaction process is completed; controlling corresponding conditions to ensure that a small part of copper and lead in the slag form lead copper matte (or black copper), depositing and discharging at the bottom of the furnace at regular time, and simultaneously enriching a certain amount of precious metals; high-temperature slag is continuously discharged from the side-blown furnace through siphoning and enters another furnace side-blown furnace or fuming furnace; the sulfide is decomposed at high temperature to produce flue gas with high sulfur dioxide concentration, the flue gas is subjected to waste heat recovery by a waste heat boiler, dust collection by electric dust collection and standard acid preparation method to prepare sulfuric acid, and the tail gas is discharged after reaching the standard.
Example two: reduction and volatilization smelting of molten slag:
a method for harmless and resource treatment of solid hazardous waste adopts a furnace, after desulfurization smelting is completed, the oxidizing atmosphere in the furnace is changed into reducing atmosphere, an air opening is added to increase the air quantity, reducing coal and silica are added into the furnace, so that metals such as lead, zinc, silver and the like in slag are reduced into metals which volatilize along with flue gas, the slag is depleted, and the control conditions in the reducing stage are as follows: the particle size of the reduced coal (coke) is 5-20mm, the oxygen-enriched concentration is 30-70%, the smelting temperature is 1100-. The slag is discharged from the discharge port.
In this example, when two furnaces are used, the molten slag after completion of the melting and desulfurization reaction is discharged from the forehearth and directly flows into the reduction furnace, and similarly, the reducing coal and the flux are continuously added into the reduction furnace, thereby completing the reduction and volatilization of the lead-containing zinc slag in the reduction furnace, and the slag after depletion is discharged from the discharge port. The flue gas produced in the furnace is subjected to waste heat recovery by a waste heat boiler, bag type dust removal is carried out, the flue gas is washed by a desulfurizing tower and then is emptied, and the lead-zinc-containing smoke dust is conveyed to a lead-zinc system to be generated.