Bead Supplier : Articles
We are an easy to shop Bead Supplier. New - Bead Supplier We offer Beads and Jewelry Supply, industry leading Bead Supplier solutions, Bead Supply information, and Bead Supplier tips. See Beads Manufacturer. Although some silver-bearing ores contain silver as their largest metal value, virtually none has silver as its main constituent. A typical ore might contain 0.085 percent silver, 0.5 percent lead, 0.5 percent copper, and 0.3 percent antimony. After flotation separation, the concentrate would contain 1.7 percent silver, 10 to 15 percent lead, 10 to 15 percent copper, and 6 percent antimony. Silver-bearing ores are mined by open-pit or underground methods and then are crushed and ground. Since virtually all the ores are sulfides, they are amenable to flotation separation, by which a 30- to 40-fold concentration of mineral values is usually achieved. Of the three major types of mineralization, lead concentrates contain the most silver and zinc concentrates the least. The smelting and converting of copper sulfide concentrates result in a "blister" copper that contains 97 to 99 percent of the silver present in the original concentrate. Upon electrolytic refining of the copper, insoluble impurities, called slimes, gradually accumulate at the bottom of the refining tank. |
Bead Supplier : More Info Lead concentrates are first roasted and then smelted to produce a lead bullion from which impurities such as antimony, arsenic, tin, and silver must be removed. Silver is removed by the Parkes process, which consists of adding zinc to the molten lead bullion. Zinc reacts rapidly and completely with gold and silver, forming very insoluble compounds that float to the top of the bullion. These are skimmed off and their zinc content recovered by vacuum retorting. The remaining lead-gold-silver residue is treated by cupellation, a process in which the residue is heated to a high temperature (about 800º C, or 1,450º F) under strongly oxidizing conditions. The noble silver and gold remain in the elemental form, while the lead oxidizes and is removed. The gold and silver alloy thus produced is refined by the Moebius or Thum Balbach process. Zinc concentrates are roasted and then leached with sulfuric acid to dissolve their zinc content, leaving a residue that contains lead, silver, and gold--along with 5 to 10 percent of the zinc content of the concentrates. This is processed by slag fuming, a process whereby the residue is melted to form a slag through which powdered coal or coke is blown along with air. High-grade jewelry scrap is usually realloyed on-site rather than being refined. Jewelry sweeps, the fine dust generated in the polishing and grinding of precious metals, are usually smelted to form an impure silver, which is electrorefined.
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