Now, capitalist and developing countries lead ore total reserves are estimated at 1.1 to 1.15 million tons, of which, according to reliable information, there are 65 million tons of lead. Modern lead mines produce between 2.45 million and 2.6 million tons per year. In this way, the proven reserves of lead can ensure that the existing production scale is only 25 to 30 years, without considering the increase in the amount of lead ore produced by lead and the increasing demand for lead-poor ore. This illustrates the importance of the most complete and rational use of lead-containing waste.
Compared with lead smelted from ore, the cost of lead extracted from waste is 38% lower, labor productivity is 1.9 times higher, and standard fuel consumption is 1/3 less.
Analysis of lead consumption from raw ore and recycled raw materials shows that 55% in the United States and 42% in Japan are used to produce lead storage batteries. Due to the strengthening of environmental protection measures, the consumption of lead production of explosion-proof additives (mainly lead tetraacetate [Pb(C 2 H 5 ) 4 ]) is shrinking. For example, in the United States, lead consumption in this area has fallen from 20.50% of total consumption to 16% in the past decade, and there is a continuing trend of compression.
A common type of lead storage battery is a case made of an acid-resistant and mechanically strong polymer (bakelite, polyethylene, polypropylene, etc.). The housing has positive and negative electrodes and is filled with solution. In order to prevent an open circuit, the electrode is separated by a separator filler, and the separator is made of microporous plastic, microporous bakelite, polyvinyl chloride or the like.
The positive electrode can be planar, armored, plate-shaped. The surface of the plate is cast with pure lead and subjected to special electrochemical processing. Therefore, the surface layer of lead is converted into lead oxide. Armor plate containing 2 to 10% gradient of cast lead alloy grid plate. 锑 can improve the mechanical strength of the grid without deformation. The grid is filled with a large amount of lead oxide. The plate piece is a grid plate cast from lead-bismuth alloy. The grid of the grid plate is coated with an active material made of lead oxide and sulfuric acid.
The negative electrode is composed of two small halves and is surrounded by a thin lead plate with holes from both sides. The grid is filled with active material.
In order to produce batteries, high-grade lead and antimony or lead-bismuth alloys are used. Metal impurities are present in the plates of the battery, and even if the amount is small, the battery is automatically discharged.
The battery pack is about 60% lead, half of which is in a metallic state, containing 3.5 to 6.0% of bismuth (plates, contacts, tabs). The remaining lead is in the form of a sulfate-oxide (the active material of the plate) containing nearly 1% bismuth. 20 to 25% of the total amount of lead storage batteries are organic materials for casings, covers, partitions, plugs, seals (bakelite, asphalt , polypropylene, polyethylene, polyvinyl chloride, fabric), and 8 to 12% are Sulfur, oxygen (sulfate and oxide) and ferrous metal (handle, handle). The chlorine content is from 1.5 to 2.0%.
The content of other elements in the undisassembled waste lead storage battery was (%): copper 0.36, calcium 0.25, magnesium 0.39, aluminum 1.1, silicon 2.3, sulfur 4.03, iron 0.81. The chlorine content is from 1.5 to 2.0%.
The composition of the active material on the positive electrode plate is: 90% of lead oxide, 7% of lead oxide, 3% of lead sulfate, and 95% of lead metal, 3% of lead oxide and 2% of lead sulfate on the negative electrode plate. During the use of lead storage batteries, especially during disassembly, the active material scatters and forms sludge. The average content of lead in the sludge is 70.8%. The doping degree of the battery pack with the electrolyte is 50%; the doping degree of the bakelite case without the electrolyte is 45%, and the thermal plastic shell is 40%.
The physical properties of the components of the waste lead storage battery vary widely. For example, the density of the lead grid is 9.4 g/cm 3 , the density of the battery sludge is 3.3 g/cm 3 , and the density of the non-metallic material is 1.44 g/cm 3 . The amount of metal portion of the waste lead storage battery is correspondingly equal to 10%; the sulfate-oxide portion is 40%, and the non-metallic material accounts for 50% of the total waste.
In recycled non-ferrous metallurgical enterprises, scrapped batteries can be disassembled or unremoved. Marine batteries are usually single-unit, and car batteries are basically a whole group. A large number of waste lead storage batteries consist of several plates and a semi-assembled part filled with active material. The plates and sludge are often impregnated with sulfuric acid.
The battery industry is now turning to polypropylene (instead of bakelite) to make battery casings and to produce new series of battery packs. The two principle different from the battery is lead-calcium alloy, are sometimes added tin, cadmium, strontium or to replace conventional lead-antimony alloy (nearly 60% antimony) producing an electrode grid.
Vacuum melting or smelting in an inert atmosphere combined with a dedicated cooling system produces alloys used to cast, roll or stamp lead battery panels. In the absence of defects in the alloy, the venting and evaporation of the electrolyte can be eliminated, and the discharge of the battery pack can be eliminated, and it must be recharged periodically.
The new battery has a small size, lead consumption of less than 25%, and a service life 1.3 times higher than lead-bismuth alloy. The new battery does not actually require maintenance.
With the large increase in the demand for lead in the production of various types of batteries, the life of the battery is 3 years for lead-acid batteries and 5 to 6 years for lead-calcium batteries. The number of waste batteries to be treated will increase year by year. Nowadays, the proportion of waste batteries in recycled lead materials has exceeded 70%.
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