Silver is recovered from pyrometallurgical refining of Ag-Zn slag. The composition of the raw materials is listed in the table below. Table Silver slag composition (%) First, the process. First, the silver in the silver residue must be further enriched, and the silver and the crucible must be separated and then the silver is extracted. The process flow is shown in FIG. Figure 1 Flow chart of silver recovery from silver slag Second, the main technical conditions. Calcination is carried out by first adding silver slag to 5 to 6% of CaO as a binder, pre-stage low-temperature roasting, temperature 550-650 ° C, time 4 hours; medium temperature slowly to 750 ° C, time 2 to 3 hours; late temperature to 850 °C, time 2 to 3 hours. The calcination is carried out in a reflective roaster. The materials in the roasting must be frequently turned over and fully oxidized. After roasting, the material is loose and granular, gray, and contains about 10% of silver. Leaching: Since the oxide of cerium and zinc is dissolved in dilute hydrochloric acid and the silver is not dissolved, the silver oxide precipitates even if dissolved. The calcined slag was ball milled to -60 mesh and leached by a two-stage countercurrent flow of dilute hydrochloric acid. One leaching: liquid-solid ratio of 3:1, hydrochloric acid concentration of 1.5%, stirring at room temperature for 1-2 hours, standing still and clarifying, and extracting the supernatant. Secondary leaching: liquid to solid ratio of 3 to 4:1, hydrochloric acid concentration of 15%, leaching temperature of about 90 °C, heat stirring for 1 to 2 hours, leaching silver slag composition is (%); Ag 80 to 85, Bi1 to 2, Zn <0.1, the silver slag rate is 96 to 98%, the leaching rate is higher than 99%, and the zinc leaching rate is higher than 99%. Reduction smelting and preliminary fire refining: smelting with heavy oil in a small converter, the melting temperature is 1200-1300 °C. Ratio of ingredients: 8-10% soda ash leached silver amount of slag; 2 to 3% sodium nitrate; reduction of 3-4% of the coal amount of slag. The smelting time is about 16 hours, and the crude silver grade (%) after slag removal is Ag93-96, Bi1~3, and Sn0.5-1. Then continue with the duct to the air bubbled into the silver solution, and add appropriate amount of Na 2 CO 3 with NaNO 3 alkaline refining, oxidative refining time 4-8 hours, when the gold to silver than 97% bonding, casting Formed as an anode plate. The direct yield of silver smelting and refining in the converter is over 95%. Silver electrolysis: the anode is covered with a double-layer polyester bag, and the cathode is made of a 2 mm thick stainless steel plate; the electrolyte composition (g/L): Ag 60-120, HNO 3 4-15, pb<], Bi 0.2-0.5: current density 250 ~ 400 A / m 2 ; groove pressure 0.6 ~ 2.2 volts, the same pole distance 6 ~ 7 cm. Silver powder is precipitated at the cathode. After the electrolyte is used for a period of time, when the impurity content is increased, the heat can be used to release the copper . The silver powder is cast into silver, and the grade is 99.95-99.99%. The silver anode contains more than 40% silver and contains about 10% gold, which is used as a raw material for gold extraction. Gold extraction: If gold is extracted by chlorination solution electrolysis, the amount of accumulated gold in the production process is too large, so it is better to use the dissolution-reduction wet method to extract gold. The process is shown in Figure 2. Third, the main equipment. One roasting reverberatory furnace, 2.6 m 2 furnace; one ball mill and two leaching tanks, one of which uses mechanically stirred jacketed enamel reactor, the other uses mechanically stirred leaching tank; one of replacement tanks: small converter One set, the silver electrolysis cell uses 30 liters of plexiglass trough; one 300 amp silicon rectifier; one set of cast furnace; one set of gold extraction equipment. Figure 2 Wet gold extraction process Rubbers And Plastics,Precipitated Silica As Rubber Filler,Powders And Granulates To Flow Freely,Prevent Caking With Long Storage Time Henan Minmetals East New Materials CO. LTD. , https://www.eastmaterials.com