The method of extracting lead from recycled materials

 

The invention relates to ferrous metallurgy, in particular to the extraction of lead from secondary raw materials, and can be used in the processing of waste resource rechargeable batteries. According to the invention in a lead bath in a reverberatory furnace continuously or periodically served oxysulfate pasta released by separating the spent cutting the life of lead-acid batteries. Download carbon-containing reductant ash content <1.0% and a particle size of <5 mm in the number of 6-7% by weight of the paste is carried out from the opposite end of the furnace, the resultant melt oxysulfate paste. The thickness of the melt oxysulfate paste is maintained in the range of 20-50 mm during the whole melting process. The accumulation of the formed slag is removed by strokes through the end window of the furnace. Process temperature smelting reduction plants 950-1050^oC. Lead, the resulting melt, after conditioning and removal from the surface of the lead oxide is responsible brand lead brand C2 or C3, is provided by the increase of direct extraction of lead from oxysulfate paste and reduce processing costs by eliminating the filing of flux. table 1.

em to be used in the processing of waste resource rechargeable batteries.

Currently, more than 50% of lead produced from secondary raw materials, mainly waste batteries. A significant part of the last before entering the melt is subjected to fragmentation with subsequent separation into individual fractions: organic, metallic and oxysulfate paste containing lead oxide in the form (b, b₂, PbS₄).

Typically, the paste is first dried (in some cases after a preliminary leaching operation to remove sulfur), then processed separately or together with the metallic fraction in various furnace units [Karl F. Lamm Secondary Lead. Erzmefall, 1998 (51), 6, s.438-455]: - plants in the United States widespread melting oxysulfate paste together with reducing agents and fluxes in a reverberatory furnace with subsequent processing of the received rich slag in shaft or electric furnace; - in the factories of Europe mainly oxysulfate pasta, pre-mixed with MaxicoM and fluxing additives (e.g., soda, lime, silica, iron scrap), melted in a rotary korotkorezannyh or rotary furnaces, a significant portion of the lead is lost with the slag. The latest in the case of the use as an additive is p>

At some plants the CIS applies Bessonova melting paste in the electric furnace with joint or separate loading recyclable material fluxes and solid reductant into the slag bath melt [Besser, A. D. and others Develop and implement electrothermal melting battery scrap without the use of soda, ensuring environmental requirements. Non-ferrous metals, 1996, 4, pp. 53-55].

In all the above methods in the melting unit are input fluxes to obtain the slag mass of a given chemical composition and specific physical properties. I assumed that this is done in order to minimize losses during the smelting of lead from the slag and matte (in the case of processing nudecoulterann paste).

The addition of fluxing materials leads to higher costs to obtain the final metal, a significant transition of lead in the slag-matte melt that requires further processing. Even in the case of obtaining the dump slag with a single-stage melting with a large mass of slag is lost to 10% of incoming to the redistribution of lead.

Known smelting secondary lead raw materials without the use of fluxes.

For example, the way in which the extraction of lead from waste lead when t is in or oxysulfate pasta with vigorous stirring during the whole process of melting, exfoliation and chemical recovery of waste. It is preferable to use a rotary Converter Caldo Gallego with top blowing, and the contents mixed by rotation of the furnace [application EPO 0132243, CL 22 In 13/00, 7/00, 1985].

The disadvantage of this method is the high consumption of reducing agent (16%) and receiving lead with a high content of antimony and arsenic, which subsequently requires significant material and energy costs to its refinement.

Closest to the claimed is a method for processing scrap batteries, on which the latter is continuously loaded into the reactor together with the reducing agent. Melting paste moisture content of 10% is carried out at a temperature of 900-1150^oWith (optimally 95020^oC) use as a reducing agent coke or coal in the amount of8% [application EPO 0196800, CL 22 In 13/02, 7/00, 1986]. When melting is not used limestone or soda. Melting and recovery is carried out with vigorous agitation uploaded to lead the bath material by feeding through an immersion lance mixture of hydrocarbon fuel and air (or oxygen), taken in an amount less than required by stoichiometry for complete combustion that is of lead metal (77%), big output slag (7%), which contains 55.7 per cent of lead and can be restored by an excess of reducing agent to lead-antimonic alloy. Over 13% of lead from the initial load takes in gases and you want to capture.

Object of the present invention is to provide an economical method of processing oxysulfate pastes, obtained after cutting the sulfuric acid batteries, allowing to increase the direct extraction of lead in metal up to 93%. A sharp decrease in the degree of transition of lead smelting in the slag and gases can significantly reduce the cost of their further processing.

This technical result is achieved in that in the method of extracting lead from secondary raw materials containing lead oxides, for example of oxysulfate paste, released by separating the spent cutting the life of lead-acid batteries, including the loading of the processed material and the solid reducing agent in the bath melt and smelted in a reverberatory furnace at a temperature of 950-1050^oWith obtaining of lead containing less than 0.5% of antimony, according to the claimed invention recyclable material and a solid reducing agent is loaded into the furnace at a bath melt separately

The essence of the proposed method is as follows.

As a result of the research it was found that separate download pasta and reductant prevents significant recovery of lead sulfate to sulfide with single-moment excess of the resulting PbS required by the reaction of PbS+2PbO=3Pb+SO₂and , as a consequence of the formation of lead matte, rolling in the slag. This leads to increased extraction of lead in the metal.

In addition, it was determined that a separate download of the reducing agent on the layer of the melt reduces its consumption due to the absence of contact of the carbon reductant with atomic oxygen released during the heat input to the kiln paste of the present there is lead dioxide, which affects the efficiency of the method.

Experiments have shown that the process of melting loaded pasta, exfoliation and chemical recovery of oxidized lead carbon reductant is contraindicated mixing, as the process is carried out in a thin layer of oxidized lead compounds due to the forces of diffusion and gravity. In the absence of vigorous stirring and maintaining the optimum thickness of the layer of the melt of the new mass does not capture the releases significant quantities of metallic lead, that leads to loss of metal from the slag.

It was established experimentally that the optimal to increase direct extraction of lead in metal is the thickness of the layer of melt oxysulfate paste on the surface of the lead bath, equal to 20-50 mm With a layer thickness of less than 20 mm violated the recovery process by MaxicoM coming in oven pasta with formation of metallic lead due to the lack of sufficient amount of liquid phase. When the layer thickness of more than 50 mm hampered the restoration of the oxide of lead compounds in the lower part of the slag layer reducing agent, which is located on the surface of the slag and the molten paste as claimed method is only due to diffusive and convective forces and no mixing. This decreases the yield of metal, drops his removal.

The invention is illustrated by the following examples.

Example 1. The process was carried out on an industrial furnace for three months.

In a reverberatory furnace with the size of the hearth 1,22.2 m²on the pre-deposited lead bath was applied oxysulfate paste after cutting waste batteries composition: Pb - 68,0; S - 5,0; H₂About to 10.0. Performance pale in the amount of 7% by weight of the paste was carried out from the opposite end of the furnace, the resultant melt oxysulfate paste. The grain size of the reducing agent 5 mm Oven was heated by burning diesel oil, furnace gorodisky brick.

Due to the presence in the incoming processing oxysulfate paste a certain amount of slag-forming, and also due to ash solid reductant and erosion of the furnace lining formed a small amount of slag melt.

Slag formed is very small, since ash used reductant was1,0%, and the content of slag in the original paste of 1.2%. The optimum thickness of the melt oxysulfate paste was determined experimentally and was maintained in the range of 20-50 mm during the whole melting process. The accumulation of the resulting slag was removed by strokes through the end window of the furnace. Process temperature smelting reduction plants oxysulfate paste 950-1050^oC.

Indicators of melting oxysulfate pastes are presented in the table.

The lead obtained by melting after conditioning and removal from the surface of the lead oxide is responsible brand lead brand C2 or C3.

Example 2. In the same reverberatory furnace was loaded oxysulfate pasta together with circulating dust, caught from the shop was 6-7% to the joint weight of dust and pasta. The process temperature of 950-1050^oC. All indicators of the smelting process were similar to the previous example. Through removing the lead from the paste in the crude metal with regard to the processing of circulating dust reached 98.7 per cent.

Thus, the developed method allows to significantly improve the direct extraction of lead from secondary raw materials, for example oxysulfate paste, and reduce processing costs by eliminating the filing of flux.

Claims

The method of extracting lead from oxysulfate pastes, including loading of the processed material and the solid reducing agent in the bath melt and smelted in a reverberatory furnace at a temperature of 950-1050^oWith obtaining of lead containing less than 0.5% of antimony, wherein the recyclable material and the solid reducing agent is loaded into the furnace at a bath melt separately, and the depth of the layer of melt oxysulfate paste on the surface of the lead bath maintained within the range of 20-50 mm