Preparation of Tin and Tungsten from Mineral Concentrates in Ionic Melts

Abstract

Features of cassiterite concentrate carbothermic reduction in melt of the salt system Na 2 CO 3 -NaNO 3 (1:0.3) are studied. It is shown that cassiterite (SnO 2 ) in molten salt (900-950ºC) is converted into the form of metastannate (Na 2 SnO 3 ) and is reduced to metal, mainly by CO gas, with a high rate and completeness (97 wt.%). Conditions are considered for preparing tungsten powder by aluminothermic reduction of scheelite concentrate in molten salts of alkali metals (It is established that powder yield is ~ 94%, and tungsten purity is 97%. It is shown that powder specifi c surface reaches 12.96·10 5 m -1 .Contemporary engineering requires the use of material exhibiting not only increased strength, but also a number of special properties (wear-, heat-, and corrosion-resistance, etc.) providing prolonged and reliable equipment operation in very different operating conditions. In order to prepare these materials from ferrous alloys (steels, cast irons, and others), it is necessary to alloy them with such elements as W, Mo. V, Ti, etc.A very promising area is development of methods for synthesizing tin and its alloys (bronzes, babbit, tin solders). The Far East region exhibits considerable mineral raw material reserves containing these elements, including tin and tungsten. In this connection, an important problem is the effective use of metal resources for production of metallic materials, and also the problem of creating new technology for preparing them with processing of tin and tungsten mineral concentrates in the areas of their recovery.An electric-arc method developed previously for obtaining tin and copper from mineral concentrates has a high energy content, prolonged preparatory processes, and other disadvantages [1]. These disadvantages may be overcome as a result of using a new method for obtaining tin.Obtaining tin by carbothermic reduction of cassiterite concentrate in molten alkali metal salts, i.e., traditional technology for producing tin metal, is a multistage process including processing ore concentrate with the aim of breaking it down, purifi cation from impurities, and subsequent reduction melting. Firing is used as preliminary treatment in order to remove sulfur and arsenic, magnetic separation is used for separating iron-containing fractions from the main mineral, and leaching is used with the aim of purifi cation from impurity elements. The concluding stage of the technology is carbothermic reduction of cassiterite, which is performed at 1200-1300ºC with the addition of fl uxes (CaCO 3 , SiO 2 ). As a result of this, alloys are obtained within whose composition there is 50-91% Sn depending on its content in the concentrate [2]. On the whole, 527 traditional technology for obtaining tin from mineral concentrates is a complex scheme, highly expensive, and does not provide suffi ciently complete tin extraction.A very advanced area is the use of alkali metal molten salts as a medium for reducing metal oxides. These melts meet to a considerable extent specifi cations for a medium within which t...

Metallothermic Reduction of Natural Cassiterite

“…5a) part of the reduced tin and excess calcium are transferred into the gas phase within which before this there is only CO(g) present. As also in the case with aluminum, calcium thermal reduction of siderite proceeds predominantly with formation of calcium monoxide (reaction (8), ΔG 1500 = -814.2 kJ/mole), and not its dioxide (reaction (7), ΔG 1500 = -499.6 kJ/mole).…”

“…There are a number of methods for obtaining tin from cassiterite concentrate among which there is extensive use of the method of carbothermal reduction [6,7]. In developing this method it is proposed [8][9][10][11][12] to use carbothermal reduction of cassiterite concentrate in molten Na 2 CO 3 -NaNO 3 salt. During reaction of cassiterite with molten salt there is formation of an intermediate compound Na 2 SnO 3 that is then reduced by carbon monoxide CO at a fast rate providing extraction of 97% Sn into black alloy [9].…”

Validation of Modification of Volumetric Methode of Determination of Sn (Tin) Concentration on Tin Concentrates

“…Contact of the solution with outside air or oxygen (O2) will directly change stannous chloride (SnCl2) to Stannic Chloride (SnCl4) which has fatal consequences in the analysis results (Sezgin, 2013). Generally, some analysts engineer Sodium Hydrogen Carbonate (NaHCO3) liquid installation systems, to prevent the solution from coming into contact with the outside air to the cooling and titration process (Gostishchev et. al, 2015).…”