Nichromet Extraction Inc.

Dundee, Technologies Durables Inc.

Dundee Sustainable Technologies Inc.

Bertrand Dubreuil

Jean-Marc Lalancette

David Lemieux

Khalil Nasrallah

There is provided a method and composition for sequestration of arsenic, the method comprising melting an arsenic-containing material in the presence of iron oxide and glass, and yielding a resulting glass incorporating arsenic. The resulting glass has an arsenic content comprised in a range between 1 and 25% w/w and an iron content comprised in a range between 8 and 20% w/w.

Method and composition for sequestration of arsenic

A method for selectively processing a polymetallic oxide solution containing a plurality of base metals comprising at least one of: Cu, Co, Ni, Zn associated with iron, comprising acid leaching the solution; recovering a filtered leachate; oxidizing the leachate; and adjusting the pH of the leachate in presence of a complexing agent; wherein the acidic solution is one of: i) a hydrochloric acid solution and ii) a sulfuric acid solution at a pH lower than about 1.5, and the complexing agent is one of: i) ammonium chloride and ii) ammonium sulfate, the step of adjusting the pH comprising raising the pH to a range between about 2.5 and about 3.5.

Method for selective precipitation of iron, arsenic and antimony

A method for extracting precious metals from a polymetallic ore, comprising a) generating hypochlorites from a salt brine; b) chlorination of the ore using hypochlorites under acidic conditions; c) filtering to collect a pregnant solution and treating the pregnant solution for collection of precious metals; d) filtering to separate the precious metals and a barren brine; e) purifying the barren brine; and f) recycling halogens from the purified brine in the form of hypohalites formed by electrolysis of the purified brine, and comprising hypochlorite and hypobromite; step b) further comprising scrubbing excess halogens using calcium hydroxide; treating the pregnant solution in step c) comprises reducing an oxydo reduction potential of the pregnant solution and using calcium hydroxide for neutralization; and step e) comprising increasing the pH of the barren brine by addition of calcium hydroxide.

Closed loop method for gold and silver extraction by halogens

A method for recovering precious metal from an acidic pregnant solution resulting from halogen or hypohalite leaching of an ore, comprising lowering the ORP of the pregnant leachate with a reducing agent in the presence of slurried non-carboneous particles. The precious metal deposits on the surfaces of the particles and a barren solution comprising substantially all the halogen values of the pregnant solution in the form of sodium chloride, sodium bromide or hypohalites is recovered.

Method and system for gold recovery

The invention relates to a method for the extraction of precious metals, using halogens. It has been found that introducing halogens in the reactor in the form of hypohalites rather than free halogens simplified greatly the recycling of halogens by electrolysis. It increases the rate of addition of the halogens and significantly reduces secondary reactions with base metals such as iron. Operating under acidic conditions, the gold recovery has been found as high with hypochlorite as with elemental chlorine, with an active chlorine to ore ratio reduced by a factor of two to five.

Method and a system for gold extraction with halogens

A method for sequestrating arsenic oxides, comprising forming an insoluble and stable glass incorporating a fully oxidized form of arsenic generated by oxidation of an initial lower oxide of arsenic and stabilization by calcium salt formation. The glass composition for sequestration of arsenic comprises from 50 to 75% silica; from 0.5 to 3% AlO; from 1 to 15% MnO; from 5 to 15% CaO; from 1 to 20% AsOand from 8 to 14% NaO, less than four percent of iron oxides, magnesium oxide and other oxides.

A method and a system for the production of potassium sulfate. The method comprises reacting a chloride of potassium with a magnesium sulfate in an aqueous alcoholic solution, with recycling of magnesium sulfate and production of hydrochloric acid, where the recycling of magnesium is done by a reaction of sulfuric acid on resulting magnesium chloride with corresponding production of magnesium sulfate and hydrochloric acid.

Method and system for the production of potassium sulfate from potassium chloride

A process for producing potassium magnesium sulfate, comprising reacting sulfuric acid with potassium chloride and magnesium chloride at a temperature in a range comprised between about 100 and about 160&#xb0; C., thereby producing potassium magnesium sulfate and hydrochloric acid, the sulfuric acid being reacted with potassium chloride and magnesium chloride simultaneously or sequentially.

Growing community of inventors

Trois-Rivières, Canada

Bertrand Dubreuil