The method of separation of platinum metals each crude single platinum group metal and the usual pyrometallurgical hydrometallurgical method of extraction from the cooperating processes concentrate the platinum group metals, respectively.
The traditional method was the main method used by the Soviet Union and the United Kingdom to separate platinum group metals before the 1980s. The technology was kept secret for nearly a hundred years and was not disclosed until the 1960s. The production cycle is long, the process is many, intermittent operation, in the process of repeated smelting, leaching, precipitation, the platinum group metals are not completely separated from each other, a large amount of precious metals are accumulated in the intermediate products, the dispersion loss is large, and the environmental pollution is serious. Since the 1970s, various countries have successively studied and adopted solvent extraction separation methods (see platinum group metal extraction separation), but the traditional methods are also commonly used to process relatively simple raw materials.
The traditional process is complicated, and pyrometallurgy and hydrometallurgy are used interchangeably. It is usually first divided into groups and then separated from each other to obtain a single crude metal or compound. The main separation step comprising roasting leach, aqua regia, platinum, palladium, gold, lead separation, the silver, a molten sodium bisulfate rhodium flooding, a flooding out fusion with sodium peroxide osmium, ruthenium, iridium aqua regia.
Calcination-leaching is an important pretreatment step in the coarse fraction. The purpose is three: 1. The content of base metal in the precious metal concentrate is reduced to less than 1% to reduce its adverse effects on subsequent operations; The grade of precious metal is increased to more than 45%, so as to reduce the processing scale of subsequent operations and reduce the consumption of reagents; 3. Convert the metals such as lanthanum, cerium and lanthanum in the concentrate to the insoluble state of aqua regia to reduce the dissolution of platinum in aqua regia. Co-dissolved and dispersed in palladium and gold. The method is enriched in sulfuric acid roasting in a platinum group metal by a sulfuric acid method. Generally, the concentrate is mixed with a small amount of concentrated sulfuric acid, and calcined in air at a temperature of 773 to 823 K for 2 to 4 hours, and then the base metal sulfate in the calcined material is leached with dilute sulfuric acid to separate it from the platinum group metal. There is a loss of oxidative volatilization during the roasting process. A small amount of dilute sulfuric acid leach when palladium, rhodium loss was dissolved in the leaching solution, zinc powder recovered replaced when needed.
The aqua regia dissolves platinum, palladium and gold with a portion of nitric acid and three portions of hydrochloric acid to dissolve the concentrate, so that gold, platinum and palladium are separately formed into HAuCl4, H2PtCl6, H2PdCl6 and the like, and the dissolution rate is above 95%. After filtration, most of the lanthanum, cerium and lanthanum remain in the insoluble slag. During the process, a large amount of cerium is oxidized to osmium tetroxide and volatilized in the gas phase. A platinum, palladium, and gold solution containing a small amount of base metal impurities is first boiled to volatilize excess residual acid, and carefully concentrated to a paste. In order to completely destroy the yellow insoluble platinum nitrosyl complex (NO2) 2PtCl6 and residual nitric acid, it is necessary to repeatedly add a small amount of concentrated hydrochloric acid to repeatedly evaporate to a paste operation until no more NO2 reddish brown smoke escapes. . The paste is dissolved in water to form a chloride solution containing gold, palladium or platinum. The gold in the solution is first reduced to metal with a reducing agent FeSO4 or SO2 and separated from the solution. The amount of FeSO4 is calculated as follows:
AuCl3+3FeSO4→Au↓+Fe2(SO4)3+FeCl3
After the crude gold is reduced and filtered, the platinum and palladium in the solution are mainly coarsely divided by the difference in solubility between the different valence ammonium salts. That is, the solution is concentrated to 30 to 50 g/L of platinum, and ammonium chloride is added to precipitate platinum (NH4)2PtCl6 with little solubility, and palladium is formed into soluble (NH4)2PdCl6. The platinum ammonium salt has the least solubility in a solution containing 17% ammonium chloride, so the amount of ammonium chloride added should be stoichiometric excess over the platinum and palladium ammonium salts. The filtered crude (NH4)2PtCl6 was washed with an ammonium chloride solution and then sent to platinum for refining. The palladium-containing filtrate can be treated by two methods: 1. Incorporating chlorine gas or adding nitric acid to oxidize soluble (NH4)2PdCl6 to insoluble (NH4)2PdCl6 precipitate (ie, Pd2+ is oxidized to Pd4+); 2. Adding excess ammonia to filtrate Neutralizing to alkaline, the palladium forms a soluble colorless dichlorotetraammine palladium complex Pd(NH3)4Cl2. After separation of the ruthenium metal hydroxide by filtration, the palladium-containing filtrate was neutralized with hydrochloric acid to pH 0.5 to precipitate an egg yellow dichlorodiamine palladium complex Pd(NH3)4Cl2. The two crude palladium complexes obtained were precipitated and sent to palladium refining. The residual liquid after separating gold, platinum and palladium still contains a small amount of gold and platinum group metals, and is replaced by zinc powder and recovered into the replacement slag. The replacement slag can be returned to the aqua regia.
The separation of lead and silver king water insoluble slag mainly contains silver, bismuth, antimony, bismuth, silicon dioxide, lead and a small amount of other precious metals. Separation of lead and silver has two methods of melting precious lead and direct leaching.
Smelting precious lead usually refers to the lead that is enriched with gold, silver and platinum group metals as precious lead. The insoluble residue was added aqua regia lead oxide or lead carbonate as trapping agent, coke as the reducing agent, sodium carbonate and borax as a flux, expensive output lead smelting reduction at a temperature of 1273 ~ 1373K. After the slag is separated, precious lead water is released and granulated, and lead and silver are dissolved with nitric acid. After filtration, sulfuric acid was precipitated by adding sulfuric acid to the solution. Silver chloride is precipitated by adding hydrochloric acid or sodium chloride to the silver-containing solution after the lead. The precipitated lead sulfate and sodium carbonate solution are boiled and converted into lead carbonate to return smelting precious lead. If the residue of lead nitrate and silver in nitric acid contains gold, platinum or palladium, it can be dissolved again with aqua regia. The insoluble slag mainly contains lanthanum, cerium and lanthanum.
The silver directly leached from the aqua regia slag is present as AgCl, and can be directly leached into a soluble silver ammonia complex by using ammonia containing 1 to 3 mol/L of ammonia. The filtered silver solution was neutralized with hydrochloric acid to precipitate a silver chloride precipitate. The slag after silver separation is leached with ammonium acetate. The filtered lead acetate solution is first boiled to evaporate acetic acid, and then sulfuric acid is added to cause lead to form a slightly soluble lead sulfate precipitate.
The sodium hydrogen sulphate is melted and leached. The slag containing mainly lanthanum, cerium and lanthanum and twice the mass of sodium hydrogen sulphate are mixed and heated to 823-873K for melting. The frit is leached with cold water to sulphuric acid. The filtered barium sulfate solution was neutralized with sodium hydroxide to hydrolyze barium hydroxide. The filtered cerium hydroxide is dissolved in hydrochloric acid and boiled to convert it to chlorodecanoic acid H3RhCl6 to obtain chlorinated acid for refining.
The sodium sulphide is melted in one water and the residue after leaching is mainly composed of strontium, barium and a small amount of strontium. Two times the sodium peroxide of its mass and twice the sodium hydroxide of its mass are added, and the mixture is between 873 and 973K. Melt at temperature. The frit was leached with water to obtain a mixed solution of sodium citrate Na2RuO4 and sodium citrate Na2OsO4. After filtration, the mash and nail were separately recovered from the solution by oxidative distillation (see 锇钌 extraction separation).
The residue of Wangshui dissolved in water and leaching nails mainly contains strontium. The hydrazine is converted to the IrO2 state when the sodium peroxide is melted, and can be directly dissolved in aqua regia to obtain a chlorodecanoic acid H2IrCl6 solution. After separating the other elements by the various methods described above, the obtained hydrazine solution is relatively pure, and the mercerized black ammonium chloroantimonate (NH4)2IrCl6 can be precipitated by directly adding ammonium chloride. The obtained ammonium chlorate is sent to refining.
Hywell Machinery company proffesional to design and manufacture the Square Vibrating Classifier/Square Vibration Sieve that include Square Vibrating Sieve,Foodstuff Square Sieve,Granule Vibrating Sieve , welcome to contact us and we will offer competitive price !
Vibration Sieving Machine main to separate the different size materials and get uniform materials. it main to install the step that after Drying Machine or Pulverizer Machine. when customer want to get uniform size materials , we will recommend the different machine to reach customer requirement, the Vibration Sieving Machine be made all stainless steel and the machine constraction also meet the requirements of GMP.
Square Vibration Sieving Machine
Square Vibration Sieving Machine,Salt Vibrating Sieve,Square Vibrating Classifier,Granule Vibration Sifter
Changzhou Hywell Machinery Co,.Ltd , https://www.hywell-dryer.com