Process to produce magnesium compounds, and various by-products using sulfuric acid in a HCl recovery loop
AssigneeAlliance MagnéSium
InventorsJoël Fournier, Laury Gauthier
Life of this patent
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Abstract
The present description relates to a process for extracting magnesium compounds from magnesium-bearing ores comprising leaching serpentine tailing with dilute HCl to dissolve the magnesium and other elements like iron and nickel. The residual silica is removed and the rich solution is further neutralized to eliminate impurities and recover nickel. Magnesium chloride is transformed in magnesium sulfate and hydrochloric acid by reaction with sulfuric acid. The magnesium sulfate can be further decomposed in magnesium oxyde and sulphur dioxyde by calcination. The sulphur gas can further be converted into sulfuric acid.
Claims19
A process for extracting magnesium sulfate from magnesium-bearing ores, comprising the steps of:
- (a) leaching the magnesium-bearing ores with HCl to obtain a slurry containing chloride compounds;
- (b) filtering the slurry to obtain a liquor containing the chloride compounds and silica;
- (c) purifying the liquor by increasing the pH by adding a neutralizing agent to produce a brine chloride solution enriched in magnesium containing precipitated iron and impurities;
- (d) filtering the brine chloride solution to extract the precipitated iron and impurities;
- (e) neutralizing the brine chloride solution to extract nickel by adding a base, to produce an enriched magnesium chloride brine;
- and
- (f) adding the enriched magnesium chloride brine to sulfuric acid to form magnesium sulfate and hydrochloric acid.
A process for extracting magnesium sulfate from magnesium-bearing ores, comprising the steps of:
- (a) leaching the magnesium-bearing ores with HCl to obtain a slurry containing chloride compounds;
- (b) filtering the slurry to obtain a liquor containing the chloride compounds and silica;
- (c) purifying the liquor by increasing the pH by adding a neutralizing agent to produce a brine chloride solution enriched in magnesium containing precipitated iron and impurities;
- (d) filtering the brine chloride solution to extract the precipitated iron and impurities;
- (e) neutralizing the brine chloride solution to extract nickel by adding a base to produce an enriched magnesium chloride brine;
- (e″) precipitating by crystallization the magnesium chloride contained in the magnesium chloride brine using dry gaseous hydrogen chloride to obtain a crystal of magnesium chloride and a solution of magnesium chloride;
- (e′″) filtering to separate said crystal of magnesium chloride from said solution of magnesium chloride;
- and
- (e″″) adding the magnesium chloride crystal to sulfuric acid to form magnesium sulfate and hydrochloric acid.
Dependencies are inferred from the claim text.