Recycled zinc production is mainly divided into new waste and old waste according to the source of raw materials. New waste material is waste produced in the smelting and processing, including zinc from galvanizing industry, wood plant copper, zinc die-casting operations, zinc wood processing industry, the production of industrial batteries dross, ash, scrap and lead, copper smelting system Slag and so on. Old waste is the waste produced after the end of the product scrap, mostly from recycled scrap remelting of galvanized products produced EAF dust, is recycled and a small amount of zinc from pressure cast zinc material. The statistics of recycled zinc production by raw materials are shown in Table 1. Table 1 China's recycled zinc is classified according to raw materials Table 1 Chinses secondary zinc production by feed supply category 2005 2006 2007 2008 2009 2010 New waste Galvanized 13 twenty two 32 29 39 47 Brass 2 2 2 2 2 2 Zinc die casting 1 2 2 2 2 3 Zinc material 1 1 1 1 1 1 Battery product 1 1 1 1 1 1 Lead, copper and other smelting systems 3 4 4 5 5 6 Subtotal twenty one 32 42 40 50 60 Old waste EAF soot 5 6 5 3 2 4 Zinc die casting 1 1 1 1 1 1 Zinc material 0 0 1 1 1 1 Subtotal 6 8 7 5 4 6 total 27 40 79 45 54 66 First, new waste (1) Hot-dip galvanizing slag and zinc ash Hot-dip galvanized ash slag is the main raw material for reclaimed zinc in China, accounting for nearly 70% in 2009. The hot-dip galvanized ash residue has high zinc content and is easy to recover, and the recovery rate is as high as 90% or more. According to the different positions of the slag in the zinc pot, it is divided into bottom slag, free slag and scum, and the zinc content is above 95%; batch galvanizing (galvanized pipe, galvanized structural parts, etc.) produces zinc ash in addition to zinc slag. Zinc ash is composed of zinc oxide and zinc, and the zinc content is also about 80%. In the galvanized product market in China in 2009, galvanized sheets accounted for 42%, galvanized tubes accounted for 20%, and zinc structural parts accounted for 38%. Considering that the consumption of galvanized structural parts in construction materials and highways has increased rapidly in recent years, the proportion of previous years has been adjusted accordingly. In addition, about 5% of the galvanized sheet production is cold-rolled, and no zinc slag is produced. According to the survey, the amount of zinc slag produced in the hot-dip galvanized sheet was calculated by an average of 3.5 kg/t, and the zinc content in the zinc slag was calculated at 94%. The zinc consumption per unit of plated parts of other hot-dip galvanized products is calculated at 5%. Only 73% of this part of the zinc is attached to the plated parts, and the remaining 16% and 11% are respectively in the zinc ash and zinc slag. The estimated results are shown in Table 2. Table 2 Estimation of ash recovery from hot-dip galvanizing residue Table 2 Secondary zinc recovery estimate in hot galvanizing zinc Industry category 2005 2006 2007 2008 2009 2010 Hot galvanized sheet Yield 803 1073 1549 1371 1881 2280 Amount of zinc slag 2.8 3.8 5.4 4.8 6.6 8.0 Zinc content 2.6 3.5 5.1 4.5 6.2 7.5 Recovery of zinc (a1) 2.5 3.4 4.8 4.3 5.9 7.1 Other hot-dip products (batch plating) Yield 846 1560 2251 1993 2734 3314 Zinc content 11.4 21.1 30.4 26.9 36.9 44.7 Recovery of zinc (a2) 10.3 19.0 27.3 24.2 33.2 40.3 Zinc content of hot-dip galvanized zinc ash slag (a1+a2) 12.8 22.4 32.1 28.5 39.1 47.4 (2) Copper material scraps The average copper product yield in China is 60% on average. A large part of the copper is copper rods, which are basically free of zinc. Only a part of the other brass materials are derived from smelting copper and zinc as raw materials, and a large part is derived from copper. Only the scraps of the new brass material are calculated in this section. 80% of the scrap in the copper processing process is directly recycled by the copper processing enterprises, and 20% is returned to the copper production stage for indirect use. Wherein the direct use of brass scrap about 90% of metallic zinc did not leave brass, 10% plus 75% of the outer metallic zinc is recycled zinc in brass indirect use as compared with the copper and zinc The value is low, 90% is not recycled, and only about 15% produces electrolytic zinc in the form of copper ash (about 30% zinc) (Table 3). Table 3 Estimation of zinc recovery from scraps from copper plants Table 3 secondary zinc recovery estimate in copper semis Industry category 2005 2006 2007 2008 2009 2010 Copper production/10kt 502.5 532.4 630.2 836.7 868.0 911.4 Zinc content/10kt 150.8 159.7 189.1 251.0 260.4 273.4 From smelting zinc production/10kt 42.8 44.6 42.4 38.0 36.2 39.5 Processing loss rate /% 40 Indirect utilization /% 20 Zinc recovery rate /% 15 Indirect use of zinc (c1) / 10kt 0.5 0.5 0.5 0.5 0.4 0.5 80 7.5 Indirect use of zinc (c2) / 10kt 1.03 1.07 1.02 0.91 0.87 0.95 The amount of zinc recovered from the copper plant (c1+c2) 1.53 1.57 1.52 1.41 1.27 1.45 (3) Die-cast zinc alloy The zinc waste generated during die casting of zinc alloy mainly comes from die-casting slag. Zinc alloy die-casting production has 5% metal loss, and also produces 4% slag. The slag is mainly sent to the zinc smelting process to manufacture zinc ingots, which is the main raw material source for die-cast zinc alloy regenerative zinc. Considering that some of the zinc castings are alloy castings, the zinc content is calculated based on 95% of the casting yield. The estimation results are shown in Table 4. Table 4 Estimation of recovery of regenerated zinc in die-cast zinc alloy Table 4 secondary zinc recovery estimate in zinc die casting Industry category 2005 2006 2007 2008 2009 2010 Zinc casting production 35.6 44.5 53.8 63.5 66.7 70.0 Zinc slag content 1.4 1.8 2.2 2.5 2.7 2.8 Zinc recovery 1.3 1.6 2.0 2.3 2.5 2.6 (4) The processing in the zinc material is basically the same as the way in which the zinc waste is produced in the process of regenerating zinc in the zinc battery, and is also some molten casting slag generated during the processing. The zinc waste in the zinc battery mainly comes from the zinc slag produced by zinc ingot casting during the processing of zinc cake and zinc plate. China's battery zinc consumption rate is about 5%, slag production rate is 4%, and molten slag is one of the raw material sources of regenerative zinc enterprises. The statistical results are shown in Table 5. Table 5 Calculation of Recycled Zinc Recovery in Zinc Battery Table 5 secondary zinc recovery estimate in zinc battery process. category 2005 2006 2007 2008 2009 2010 Ordinary zinc battery production / 100 million 198 210 235 250 233 256 Zinc content in the battery/10kt 15.6 15.9 16.7 17.5 16.0 17.3 Zinc content of zinc residue / kt 0.7 0.7 0.7 0.7 0.7 0.7 Zinc recovery / kt 0.6 0.6 0.6 0.7 0.6 0.7 (6) Lead and copper smelting systems Since zinc and lead metals are always associated with ore, zinc is enriched in soot during lead smelting, which is also the raw material for regenerative zinc. In addition, in the copper smelting system, because of the presence of waste brass, zinc is also enriched in the flue and becomes a raw material for reclaimed zinc. Second, the old waste (1) Zinc-containing soot in steel mills This part mainly produces zinc oxide and some chemical products by sintering in a rotary kiln and a kiln. Zinc-containing soot is mainly from blast furnace ash, converter ash and electric furnace. The electric furnace is mainly used, because the electric furnace is mainly used to refine scrap steel, the zinc content in the electric furnace ash is about 15%; the converter also has a part of scrap steel, but the zinc content is low, generally in the fraction of a few to a few points; blast furnace ash The amount of zinc contained is also 7% to 8%, but this depends on the type of raw materials, and the amount of zinc in different steel mills varies greatly. In general, the zinc of soot is mainly from the electric furnace. The specific data is shown in Table 6. Table 6 Statistics of zinc-containing soot Table 6 secondary zinc recovery estimate in EAF dust category 2005 2006 2007 2008 2009 2010 Electric arc furnace crude steel production 5298 5868 5969 6006 6783 7326 Electric arc furnace soot production 86 96 97 98 110 119 Soot utilization 29 37 32 18 14 26 Zinc content 5.9 7.3 6.5 3.7 2.8 5.3 Zinc recovery 5.0 6.2 5.5 3.1 2.4 4.5 Table 6 is the value of soot according to galvanized steel. In the actual production of steel mills, it is unlikely that all the steel scraps will be galvanized steel, and according to the proportion of galvanized steel in the production of crude steel, the recovery of scrap The proportion of medium-zinc steel is also less than 5%, and the environment in the southern coastal areas is humid, and the proportion of galvanized steel used and recycled is higher than that in the north. According to the survey, the amount of zinc that can be used in general is 8% to 18%. The reason for the sharp drop in soot utilization in 2008 and 2009 was the sharp drop in zinc prices. The profit from the production of sub-zinc oxide by this method was greatly reduced. Until the second half of 2009, some factories gradually resumed production. (2) Zinc alloy die castings The depreciated and reclaimed zinc resources of zinc alloy die-casting products mainly come from depreciated zinc alloy die-casting product wastes, such as scrapped auto parts and household electrical appliances. Most of them are not suitable for the reuse of the die-casting industry, but the zinc ingots are sent to the zinc smelting process. The recovery rate of China's depreciated zinc alloy die-casting products is estimated to be about 65%. (3) Zinc material Depreciated zinc in zinc is derived from depreciated zinc scrap, including waste rolled roof sheets, printed zinc sheets, and offset zinc sheets. This part of the waste zinc is mainly sent to the smelting process to produce remelted zinc ingots. Estimated China's depreciated zinc recovery rate is about 65%. Magnetic gear pump,High Quality Magnetic gear pump,Magnetic gear pump Details, CN Botou Honghai Pump Co.,Ltd , http://www.pumphonghai.com