Minerals Engineering, Vol. 5, No. 9, pp. 1079-1081, 1992 0892-6875/92 $5.00+0.00 Printed in Great Britain Pergamon Press Ltd

NEW PATENTS

This Section contains abstracts and, where appropriate, illustrations of recently issued United States patents and published patent applications filed from over 30 countries under the Patent Cooperation Treaty. This information was obtained from recent additions to the Pergamon PATSEARCH ~ online database in accordance with interest profiles developed by the Editors. Further information about Pergamon PATSEARCH ~ can be obtained from Pergamon Orbit InfoLine Inc., 8000 Westpark Drive, McLean, Virginia 22102, U.S.A.

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4985216

REDUCTION ROASTING OF METAL ORES

Tawil Mamdouh M El, Adrian E Albrethsen as- signed to ASARCO Incorporated

A process is provided for the reduction roasting of ores using a C2 to C8 hydrocarbon. The pro- cess is particularly applicable to manganese dioxide containing ores and provides enhanced reduction of the manganese to lower oxidation states at low operating temperatures for man- ganese dioxide ores and provides increased silver recoveries from refractory manganese-silver ores.

4987081

CHEMICAL/BIOLOGICAL PROCESS TO OXIDIZE

MULTIMETALLIC SULPHIDE ORES

Ralph P Hackl, Frank R Wright, Albert Bruynesteyn, North Vancouver, Canada as- signed to GB Biotech Inc

This application relates to an improved method for oxidizing multimetallic sulphide ores and concentrates, using a combination chem- ical/biological leaching process and at least three different types of bacteria. The treatment pro- cess for multi-metallic ores such as arsenopyrite can be made to work rapidly and to as much as 98~ sulphide oxidation, when the finely ground ore or concentrate is leached in agitated, air spar- ged tanks, with strains of three different bacteria, T. thiooxidans, T. ferrooxidans, and Leptospiril- lum ferrooxidans. L. ferrooxidans is quite similar to T. ferrooxidans and obtains its energy for growth from the oxidation of ferrous iron.

The process of the invention may conveniently be a continuously operating process utilizing more than one stage. Most of the chem- ical/biological action using the bacterium T. thiooxidans preferably takes place in the first stage, while in the subsequent stages the activity ofT. thiooxidans is decreased in favour of the ac- tivity of the bacteria T. ferrooxidans and L. fer- rooxidans, which oxidize the by then more readily available sulphide portion of the pyrite minerals present in most arsenopyrite ores and concentrates. According to the invention, bac- terial cultures ofT. thiooxidans, T. ferrooxidans and L. ferrooxidans used are first adapted to high dissolved arsenic concentrations and low pH by subjecting the cultures in a solution con- taining dissolved arsenic, to successive incremental concentrations of arsenic while operating in a continuous mode.

4988079

APPARATUS FOR SMELTING AND REDUCING IRON ORES

Kenj Takahashi, Katsuhir Iwasaki, Shigeru In- oue, Haruyoshi Tanabe, Masahir Kawakami, Kenzo Yamada, Ichiro Kikuchi, Tokyo, Japan assigned to N K K Corporation

An apparatus for smelting reduction comprising a preheat and prereduction furnace for pre- heating and prereducing iron ores; a smelting reduction furnace into which iron ores, car- bonaceous material and fluxing material are charged and in which the iron ores are smelted and reduced; a top-blow oxygen lance through which oxygen gas is blown into the smelting reduction furnace, having decarbonizing nozzles and post combustion nozzles; and the smelting reduction furnace having bottom and side tuyeres built respectively in a side wall and a bot- tom thereof.

1079