1352 New Patents

4976939 PROCESSING OF RARE EARTH

ORES

Frederi Fabre, Jean-Paul Tognet, Claude Magnier, Paris, France assigned to Rhone- Poulenc Specialites Chimiques

Rare earth hydroxides are recovered from the rare earth ores, e.g., monazite, xenotime and/or bastnasite, by treating the ore with an aqueous solution of an alkali metal hydroxide, under agitation and essentially constant pressure, at a temperature of from about 100 degrees to 220 degrees C., and wherein the ratio by weight of alkali metal hydroxide/ore ranges from about 1.4 to 0.5, e.g., a weight ratio of sodium hydro- xide/ore of from about 1 to 0.5, or a weight ratio of potassium hydroxide/ore of from about 1.4 to 0.7.

4979987 PRECIOUS METALS RECOVERY

FROM REFRACTORY CARBONATE ORES

Peter Mason, Patrick O'Kane, Robert Pen- dreigh, North Vancouver, Canada assigned to First Miss Gold Inc

Precious metal values, particularly gold and sil- ver, are liberated from refractory, carbonate ores by adjusting the molar ratio of sulfide to total acid consumers to between about 1.2 and about 3.2 in the ore feed to a pressure oxidation pro- cess. The ore is contacted with oxygen to oxidize sulfide in the ore with at least about 65 percent of the sulfide oxidation occurring in a first oxida- tion zone at a temperature above about 360 degrees F. The oxidation of sulfide forms at least about 5 grams of free sulfuric acid in the first ox- idation zone. The oxidation process is continued in subsequent oxidation zones. A gas stream is removed from the oxidation zones and oxygen is separated from carbon dioxide and other inerts in the gas stream and the purified oxygen is recy- cled to the oxidation zones.

4979986

RAPID OXIDATION PROCESS OF CARBONACEOUS AND PYRITIC

GOLD-BEARING ORES BY CHLORINATION

David L Hill, Kenneth A Brunk assigned to Newmont Gold Company and Outomec U S A Inc

A method of treating a gold-bearing ore to ren- der the gold component of the ore more amenable to standard cyanidation treatment in a reduced amount of time is disclosed. An aqueous slurry of the gold-bearing ore is introduced into at least one vessel. An oxidizing agent, such as chlorine gas, an alkali metal hypochlorite and an alkaline earth metal hypochlorite, is rapidly in- troduced into the vessel so that it intimately con- tacts the aqueous slurry. While the oxidizing agent is being introduced into the vessel, the slurry is agitated with agitating means including a plurality of impeller blades that provide high shear agitation and a large interfacial surface area between the oxidizing agent and the liquid phase of the slurry to enhance the mass transfer of the oxidizing agent so that it becomes substan- tially completely adsorbed by the aqueous slurry in about 5 to about 15 minutes.

4981398

DUST S U P P R E S S A N T FOR MINERALS

John R Field, Geoffrey S Gagen, West Yor- kshire, United Kingdom assigned to Allied Col- loids Ltd

Oil dispersions of water-soluble anionic polymer particles and water-soluble cationic polymer particles are mixed with water to form an aqueous solution containing one polymer in an amount in the range 10 to 40 mole % (moles of anionic groups) and the other polymer in an amount in the range 60 to 90 mole %. The solu- tion is immediately applied to a surface to sup- press release of dust from that surface.