The process of extracting cerium, lanthanum and tungsten enrichment from tin reduction smelting slag. One by-product of the processing content of tin metallurgy, but only those rich tin smelter processing of tantalum, niobium, tungsten concentrate produced slag party recovery value.
Tin, bismuth and tungsten contained in the tin slag composition in the tin concentrate are in the form of oxides entering the slag during the reduction smelting. Due to the different tin concentrate composition, the amount of bismuth, bismuth and tungsten contained in the slag fluctuates greatly (see table). .
Process Flow There are two types of methods for recovering bismuth, antimony and tungsten from tin slag. The metallurgical method can be divided into various processes.
Method smelt slag after crushing was added tin smelting reduction in an arc furnace coke obtained containing tantalum, niobium, iron-carbon alloy carbides. After the iron alloy is crushed and ground, magnetic separation is performed to separate the non-magnetic substance, followed by adding hydrochloric acid to dissolve the impurities, and then filtering, drying and calcining to obtain the cerium and lanthanum oxide concentrate. By treating slag containing about 4% of each of cerium and lanthanum oxides by this method, a concentrate containing about 60% of total cerium and lanthanum oxides can be obtained.
The tin slag can also be firstly selected by shaker, magnetic separation and electrostatic beneficiation and then enriched by electric furnace. When the tin slag contains Ta 2 O 3 of 2% to 15%, it can obtain Ta 2 O 5 20% to 30%. Concentrate.
Metallurgical method There are various processes such as sodium carbonate roasting, one water leaching, one acid leaching, acid leaching, one acid decomposition, reduction one oxidation, reduction electrolysis, carbonization, low temperature chlorination and reduction acid treatment.
(1) Sodium carbonate roasting - water leaching - acid leaching. The tin slag is mixed with 40% sodium carbonate and 6% charcoal, and after grinding, it is calcined at a temperature of 1123 to 1223 K. The calcined material was wetted and leached with water, and the leaching temperature was 363 K, and most of the tungsten was removed by leaching for 1 hour. Tantalum and niobium-containing residue obtained after filtration silicic acid leaching with 7% to 9% hydrochloric acid, the silicon removal rate of 60 ~ 70. The de-siliconized filter residue is digested with a solution containing 12% to 14% hydrochloric acid at a temperature higher than 363 K, and the tin removal rate can reach 50% to 70%, and impurities such as iron, manganese , molybdenum , magnesium , and calcium are simultaneously removed. Processing this method comprising Ta 2 O 5 4% ~ 6 %, Nb 2 O 5 3% ~ 4% of the starting material, is obtained containing (Ta, Nb) 2 O 5 more than 40% of tantalum and niobium enrichment.
A similar method, after water leaching, acid leaching at a temperature of 333 K with a mixture of hydrochloric acid and sulfuric acid of 1 mol/L, which can be self-contained in tin slag containing Ta 2 O 5 4.2% and Nb 2 O 5 5%. An enrichment containing 11.3% of Ta 2 O 5 and 36% of Nb 2 O 5 was obtained.
The resulting sodium tungstate solution can be leached with water to recover tungsten. One method is that the leachate is filtered and treated with a strong basic anion exchange resin and desorbed to obtain an ammonium tungstate solution, and the solution can be used to prepare ammonium paratungstate. Hydrochloric acid, ammonium chloride and magnesium chloride may be added to the sodium tungstate solution, followed by boiling, and the heated clarified supernatant is added with a saturated calcium chloride solution to obtain an artificial scheelite .
The filtrate obtained by desulfurization of hydrochloric acid firstly reduces the Sn 4+ to sn 2+ by iron, and then electrolytically deposits with an insoluble anode to obtain a cathode tin containing 75% to 85% of tin. The process flow for recovering tantalum, niobium and tungsten from tin slag is shown in the figure.
(2) Acid leaching - acid decomposition. The tin slag is leached with dilute sulfuric acid (<10%), and the leaching slag containing cerium and lanthanum is decomposed with 98% concentrated sulfuric acid and ammonium sulfate. By this method, a cerium-rich concentrate containing Ta 2 O 5 16.2% and Nb 2 O 5 7.2% can be obtained from tin slag containing Ta 2 O 5 3% to 9% and Nb 2 O 5 3% to 10%.
(3) Reduction-oxidation. After the tin slag is crushed, coke is added and reduced and smelted in an electric arc furnace to obtain an enrichment of bismuth carbide. The ruthenium enriched material is then crushed and then sodium nitrate is added for oxidative smelting. The oxidized smelting product is leached with water to remove impurities such as silicon, titanium , aluminum , tungsten, etc., and the slag containing sodium citrate and sodium citrate is leached with 20% hydrochloric acid to remove iron and excess alkali to obtain a cerium hydroxide-rich material. By this method, tin slag containing 3.85% of each of Ta 2 O 5 and Nb 2 O 5 is treated, and an enrichment containing 40% to 50% of (Ta, Nb) 2 O 5 can be obtained.
(4) Reduction-electrolysis. The tin slag is added with 60% iron pyrite calcined product, coke and limestone , and is subjected to reduction smelting at a temperature of 1673 K to obtain an iron alloy containing cerium, lanthanum and tungsten, and tin enters the soot. In an electrolytic solution composed of FeCl 2 -HCl-(NH 4 ) 2 SO 4 , an iron alloy is used as a soluble anode for electrolysis, and ruthenium, osmium and tungsten are introduced into the anode slime to obtain an enriched product. This enriched product was washed successively with petroleum and sodium carbonate solution for desulfurization. In this way, the enrichment of Ta25%, Nb30% and W24% can be obtained from tin slag containing Ta 2 O 5 1.7% to 2.1% and Nb 2 O 5 2.3% to 3.5% and WO 3 1% to 3%. Object.
(5) Carbonization - low temperature chlorination. The tin slag is crushed and mixed with coke, and heated and sintered at a temperature of 1473 to 1723 K in a neutral or reducing atmosphere. The obtained ruthenium and osmium carbides are chlorinated with chlorine gas at a temperature of 673 to 773 K, and sulfur, calcium, aluminum, and magnesium are left in the slag, and metal chlorides such as ruthenium, osmium, titanium, and iron are volatilized into the furnace gas and collected. The titanium is separated by the difference in boiling point of the chloride, and the iron is separated by separate precipitation. By this method, an enrichment containing Ta 2 O 5 20.7% and Nb 2 O 5 29.2% can be obtained from a tin slag containing Ta 2 O 5 1.9% and Nb 2 O 5 2.8%.
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