RU2164537C1 - Method of processing lead cell scrap - Google Patents

Abstract

FIELD: nonferrous metallurgy, particularly, processing of obsolete lead cells. SUBSTANCE: method includes grinding of scrap in flow of circulating water, wet material sizing, separation into organic, oxide-sulfate and metallized fractions with subsequent electric smelting of two latter fractions and classification of organic fraction into light and heavy fractions. Oxide-sulfate fractions is subjected before electric smelting to additional reduction to size of minus 0.04 mm, and fraction of lead oxides is separated with withdrawn from process in the form of marketable intermediate product. In peculiar cases of the invention realization, sulfate component before smelting is subjected to desulfation, and heavy organic matter is withdrawn from polluted circulating water into dump product. EFFECT: reduced lead losses and ecologically harmful effluents of sulfur dioxide gas, increased efficiency of process and reduced economic expenditures. 3 cl

Description

 The invention relates to ferrous metallurgy, in particular to the recycling of lead batteries that have expired.

 In lead-acid batteries, gratings, contacts, jumpers are made of metal antimony lead, the active mass of the electrodes is a paste of metallic and oxidized lead, the battery housing and insulator gaskets of separators are organic. During operation, with the active mass of the electrodes, phase transformations occur and the batteries become unusable.

 A known method of processing scrap lead batteries, in which, after removal of sulfuric acid and separation of the battery housings (organic matter), the raw materials are heated until the metal fraction is smelted from it, which is drained through the bottom separators of the containers; the remaining oxide-sulfate fraction is subjected to reduction smelting (RF patent N 2070590, bull. N 35, 1996).

 In another known method, a metallized and sulfate oxide fraction is first isolated from spent batteries and then electrically melted in the presence of a reducing agent and flux (ed. St. N 996488, bull. N 6, 1983).

 The disadvantages of these processing methods are significant losses of lead due to dust and slag that appear during smelting, as well as the formation of environmentally hazardous sulfur dioxide gases that require disposal. In addition, organic wastes containing such a valuable component as polypropylene are not processed and go entirely to the waste product. The methods require significant economic costs.

 Closest to the claimed is a method of processing lead-acid scrap, including preliminary cutting of scrap before smelting by grinding and wet sieving of material by size into fractions of -60 + 1 mm, -6 + 1 mm and -1 mm. The first two classes, containing metallic lead and the bulk of the organics, are subjected to separation in an upward flow of circulating water. The -1 mm class contains mainly an oxide-sulfate fraction. As a result, the initial scrap is divided into two lead-containing fractions - metallized and oxide-sulfate and the fraction containing organic matter. (Mechanized preparation of scrap lead batteries for metallurgical processing. Journal of Non-Ferrous Metals, 1990, N 12, pp. 41-43). Lead-containing fractions are subjected to reduction electric melting. In this case, the metallized fraction with a content of 90% Pb and 4-5% Sb can be reused in the manufacture of battery plates and lead oxide is obtained from the oxide-sulfate fraction. Polypropylene is recovered from organics for reuse.

 This method, which is adopted as a prototype, allows partial processing of organics, however, it is also characterized by losses of lead during smelting and significant economic costs, including the elimination of harmful emissions of sulfur dioxide.

 The technical result achieved by the implementation of this invention is to reduce losses of lead and environmentally harmful emissions of sulfur dioxide. At the same time, additional commercial commodity product is obtained. The extraction of valuable components from the organic fraction is achieved no worse than in the prototype. In general, there is a decrease in economic costs and an increase in the efficiency of the process of processing scrap battery.

 The claimed result is achieved by the fact that in the known method of processing lead-acid scrap in a stream of recycled water, including grinding, wet sieving of material by size into fractions, separation of fractions into organic, oxide-sulfate and metallized, followed by electric melting of the latter two and classification of the organic fraction into light and heavy fractions, according to the invention, before electric smelting, the oxide-sulfate fraction is subjected to additional grinding to a particle size of 0.04 mm and is isolated from it share of oxides of lead, which is removed from the process as a ready marketable industrial product.

 In the particular case of the invention, after the separation of lead oxides from the oxide-sulfate fraction, the remaining sulfate component is subjected to desulfation before electric smelting.

 In another particular case of the invention, the heavy organics contained in it are recovered from the contaminated circulating water into the waste product.

 It was found that with additional grinding of the oxide-sulfate fraction to a particle size of 0.04 mm, a fine fraction of lead oxides with a content, wt% can be directly isolated from it, wt%: lead oxides 65-75; metallic lead up to 2-3 (with an oxidation state of 75-85%), lead sulfate up to 20, metallic impurities 0.01-0.1. It turns out commodity industrial product in the form of a powder, which is removed from the process.

 According to the standard scheme for the processing of accumulated scrap, the resulting oxide-sulfate fraction is subjected to electric smelting, refining, bottling, gas and dust collection at a lead plant to produce branded lead in pigs. In the proposed method, the production and removal from the process without the electric melting stage of the finished intermediate product - a fine fraction of oxidized lead - 0.04 mm, can significantly reduce lead loss. Given that the fraction of lead oxides in the oxide-sulfate fraction is approximately 60 wt.%, These losses are reduced by no less than 5%. At the same time, emissions of sulfur dioxide are also reduced, which allows to improve the ecology of the process. The proposed method is cost effective.

 Additional process efficiency due to reduction of losses of lead with matte and reduction of sulfur dioxide emissions can be achieved by desulfation of the sulfate component before melting.

 Extraction of polyvinyl chloride particles polluting it from recycled water has a beneficial effect on the efficiency of processing scrap battery by this method and improves the environment.

 The resulting industrial product may find application, for example, in a battery plant. The active mass of the battery consists of fine powders of metallic lead, lead oxides and binders. At present, fine powders are obtained from branded lead in special thermal installations by melting it with simultaneous oxidation. The phase (oxidation state of lead) and particle size distribution of the intermediate obtained by the proposed method shows that it can find effective application in the production of active mass of batteries.

 The claimed combination of essential features, as well as its impact on the specified technical result is not known from sources of information.

 The invention is illustrated by the following examples, which, however, do not exhaust all the possibilities of carrying out the invention, characterized by the combination of features given in the claims.

Example 1
5 tons of battery scrap are crushed to -70 mm, and then they are classified on a vibrating screen into two classes -70 + 1 mm and -1 mm. Class -70 + 1 mm in the stream of circulating water is divided into a metallized fraction containing antimony lead (Pb - up to 94%; Sb - up to 6%), and an organic fraction. The metallized fraction is sent to electrofusion. The organic fraction, in turn, is classified into a light fraction of +1 mm containing valuable components such as polypropylene, polyethylene, ebonite, and a heavy fraction of -1 mm containing polyvinyl chloride, which is sent for disposal.

Lead-containing pulp with a grain size of -1 mm, which is approximately 3.3 m ³ , is subjected to additional grinding in a drum classifier mounted on a central shaft rotating at a speed of 5-7 rpm. The drum classifier allows only oxide-sulfate mass to be selectively rubbed to a particle size of 0.04 mm, while the solid particles of lead-antimony lattices and organics contained in this fraction in a small amount do not decrease in size.

The result is about 0.1 m ^{3 of} sand with a particle size of -1 mm, which is separated and sent to the metallurgical redistribution, and discharge - 0.04 mm in an amount of 3.2 m ³ . The drain is diluted with circulating water to a solids content of 100-150 g / l and sent for separation on a concentration table by specific gravity to obtain a lead oxide pulp (in an amount of about 1.7 m ³ ) and a sulfate component pulp (in an amount of about 1.5 m ³ ). At the same time, the quality of separation is visually adjusted by color, because the fraction of lead oxides is yellow to light green in color. 0.4 tons of cake with a moisture content of 15%, containing about 70 wt.%, Were obtained from the pulp of lead oxides after dehydration. % lead oxides, 2-3 wt.% metallic lead with a degree of oxidation of 75-85%. The particle size (95%) is 0.04 mm. The cake is taken out of the technological process in the form of a commercial product, which can be used to obtain the active mass of batteries. The remaining sulfate component is sent to a reduction electrofusion to produce grade lead.

Example 2
Grinding, classification and separation of battery scrap into metallized, organic and oxide-sulfate fractions is carried out as in example 1. In a similar way, the metallized fraction is sent to electric smelting, and valuable components and polyvinyl chloride are isolated from the organic fraction. After additional grinding, -1 mm after additional grinding in the drum classifier, sands are separated, which are removed from the process and sent to the metallurgical redistribution. Drained from sand, a particle size of -0.04 mm is diluted with circulating water and separated on a concentration table into fractions of lead oxides and a sulfate component. Oxides of lead are dehydrated and removed from the process as a finished intermediate containing 75 wt. % lead oxides, 2-3 wt.% metallic lead with a degree of oxidation of 75-85%. The particle size (95%) is 0.04 mm. The sulfate component is subjected to desulfation in a solution of NaOH, Na ₂ CO ₃ and reductive electrofusion.

Example 3
0.5 tons of battery scrap is subjected to grinding, classification and separation, as in Example 1. The metallized fraction containing up to 94% Pb and up to 6% Sb is sent to electric melting. Polypropylene, polyethylene, ebonite are isolated from the organic fraction as a commercial product. The heavy fraction containing polyvinyl chloride is sent for disposal. Lead-containing pulp with a particle size of -1 mm, which is approximately 0.3 m ³ , is subjected to additional grinding in a drum classifier. The resulting sands with a particle size of -1 mm in an amount of 0.01 m ³ are separated and sent to the metallurgical redistribution. Drain - 0.04 mm in an amount of 0.29 m ^{3 is} diluted with circulating water to a solids content of 100-150 g / l and is sent for separation on a concentration table by specific gravity to obtain a lead oxide pulp and a sulfate component pulp. After dehydration, lead cake is taught from the pulp of lead oxides, which is removed from the technological process in the form of a commercial intermediate product. Cake contains 75 wt.% Lead oxides, 2-3 wt.% Metallic lead with an oxidation state of 75-85%. The particle size (95%) is 0.04 mm. The remaining sulfate component is sent to a reduction electrofusion to produce grade lead. During the process, particles of polyvinyl chloride contaminating it are removed from the circulating water, which are sent for disposal.

 Thus, the proposed method of processing battery scrap eliminates the stage of remelting in relation to part of the processed material, which is removed from the process in the form of a finished industrial product. Due to this, lead losses are reduced by no less than 5%. The process is more environmentally friendly by reducing the accompanying smelting emissions of sulfur dioxide. Significantly reduced energy costs and the cost of disposal of harmful substances.

 The phase and particle size distribution of the obtained intermediate product allows, in particular, to be used in the production of the active mass of the batteries, as a result of which the cost of their manufacture is reduced.

Claims (3)

 1. A method of processing lead accumulated scrap in a stream of recycled water, including grinding, wet sieving of material by size into fractions, separation of fractions into organic, oxide-sulfate and metallized followed by electric smelting of the latter two and classification of the organic fraction into light and heavy fractions, characterized in that before electric melting, the oxide-sulfate fraction is subjected to additional grinding to a particle size of 0.04 mm and a fraction of lead oxides is isolated from it, which is removed from the process into de commodity middlings.  2. The method according to claim 1, characterized in that the sulfate component of the oxide-sulfate fraction is subjected to desulfation before melting.  3. The method according to claim 1 or 2, characterized in that the heavy organic matter contained in it is removed from the contaminated circulating water into the waste product.