Other

Vale S.a.

Vale Inco Limited

Salomão Solino Evelin

Roberto Mattioli Silva

Marcelo Augusto Castro Lopes Da Costa

Omar Antunes Do Carmo

Vanessa Torres

Geraldo Luiz Da Silva

Clauson De Souza

Vanessa Macedo Torres

A method for treating liquid effluents and recovering metals is described, which comprises the steps of: a) liquid effluent equalization; b) sulphide addition and precipitation of metals in the form of metal sulphides; c) solid/liquid separation of the metal sulphides produced in step (b) and formation of a metal-free liquid phase; d) addition of a 50 to 250 g/L amine solution to the liquid phase precipitating magnesium in the form of magnesium hydroxide (Mg(OH)2); and e) recovery of amine by stripping and rectification.

Process for treating liquid effluents and recovering metals

Method for production of metallic cobalt from the raffinate from solvent extraction of nickel'. Said method comprises the following stages: (A) obtaining the raffinate from solvent extraction of nickel, for production of cobalt; (B) adding a sulfide precipitation agent to said raffinate, for cobalt sulfide and zinc sulfide precipitation; (C) removing all ammonia from the sulfidized pulp (solids and liquid); (D) subjecting the filtered solid&#x2014;cobalt sulfide (and impurities)&#x2014;to atmospheric leaching; (E) reducing to a minimum the zinc concentration in the cobalt round, by means of solvent extraction with D2EPHA extractant diluted in solvent, in any solvent extraction system comprising the required number of extraction, scrubbing, and stripping stages, with resident time of not less than 1 minute at each of the stages used; (F) performing nickel removal by ion exchange, for nickel purification; (G) adding sodium carbonate to the solution, for cobalt carbonate precipitation; (H) leaching the produced cobalt carbonate in a system that utilizes an acid, preferably sulfuric acid, and more preferably, the anolyte from cobalt electrolysis; (I) performing cobalt electrowinning so as to recover the cobalt from the solution in its metallic form; and (J) allowing the metallic cobalt to settle on insoluble stainless steel plates during the time required for production of the cobalt cathodes.

Method for production of metallic cobalt from the nickel solvent extraction raffinate

The present invention concerns a process for the instantaneous control of the precipitation of nickel and cobalt present in a leach liquor by adjustment of the pH-value. Said leach liquor is obtained by pressurized acidic leaching of laterite ores and additionally contains aluminium, ferric and ferrous iron and chromium among others. The process comprises the following steps: precipitation of aluminium, ferric and ferrous iron, chromium etc. by increasing the pH-value by adding a suitable reagent such as lime and/or limestone, following precipitation of nickel and cobalt by further increasing the pH-value of the liquor, finally separating the precipitate from the low-content nickel and cobalt solution. The nickel and cobalt precipitate can be used for further refinement. In order to keep the process conditions constant, the steps of increasing the pH-value are controlled simultaneously.

Process for the instantaneous control of precipitation of nickel and cobalt present in the leach liquor, by adjusting the pH of the solution

A process for recovering metals such as Ni, Co, Mn, Cu, Zn, among others, through precipitation as sulphides, enabling recovery of magnesium in the form of hydroxide, carbonate and oxide and providing recovery of sulphate as gypsum and ammonium sulphate. Liquid phase, after full treatment, comprises recovered water with a quality proper for total reuse in industrial process. This process of liquid and solid effluent treatment is provided with flexibility to process several types of effluents presenting wide variations in their chemical composition. The main steps of this process are: (1) equalization of liquid effluent, (2) precipitation of metals as sulphides, (3) oxidation of metallic sulphides and crystallization as metallic sulphates, (4) precipitation of magnesium as hydroxide and calcination thereof into magnesium oxide (5) recovery of ammonia, (6) preconcentration of the remaining saline solution, (7) evaporation/crystallization of ammonium sulphate, (8) storage of recovered water, (9) partial or total precipitation of sulphate contained in the effluent with quicklime, (10) segregated storage of gypsum and gypsum-magnesium mixture, (11) softening of the remaining solution and (12) storage of softening water.

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Belo Horizonte, Brazil

Salomão Solino Evelin