KINETIC ASPECTS OF THE CHLORINATION OF WOLFRAMITE AND OF SCHEELITE WITH CHLORINE AND SULFUR-DIOXIDE

The chlorination of wolframite and of scheelite with chlorine (chlorin ation agent) and sulphur dioxide (reducing agent) was studied within t he temperature range 673-1173 K. The tests were carried out in a verti cal reactor with a static bed. The greatest tungsten extractions (1173 K) were 86% from wolframite and 33% from scheelite. The behaviour of the chlorination reactions was analyzed through characterization of th e reaction products obtained in each case. The principal reaction prod ucts identified were WO2Cl2, FeCl3, CaSO4 and CaCl2. Likewise, size ch anges, specific surface areas and surface contents of calcium, tungste n, iron and manganese of both ores were studied during chlorination. B y means of kinetic models it was determined that the wolframite chlori nation is controlled by the movement of an interface and that the pres ence of reaction products affects the scheelite chlorination. Finally, a possible stoichiometry was proposed to explain the reaction of oxyg en contained in the wolframite and in the scheelite.