Minerals Engineering, Vol. 6, No. 4, pp. 437 -438 , 1993 0892-6875/93 $6 .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 application filed from over 30 countries under the Patent Cooperation Treaty. This information was obtained from recent additions to the PATSEARCH ® online database in accordance with interest profiles developed by the Editors.

Further information about online patent searching can be obtained from Research on Demand, Inc., 2421 Fourth Street, Ste. C., Berkeley, CA 94710, U.S.A. [Tel. 510-841 1145; Fax 510-841 6311].

5130037

PROCESS FOR THE FROTH FLOTATION OF OXIDE AND SALT TYPE MINERALS AND

COMPOSITION

Piot Swiatowski, Anne Andersen, Anneli Asken- bom, Huddinge, Sweden assigned to Berol Nobel AB

A process is provided for the froth flotation of oxide and salt type minerals utilizing as the col- lector a combination of a monoester of a dicar- boxylic acid of the general formula See Patent for Chemical Structure I in which R' is an aliphatic hydrocarbon group with 7-21 carbon atoms, R" is a hydrocarbon radical with 2-6 car- bon atoms and A is an alkylene oxide group derived from an alkylene oxide with 2-4 carbon atoms; and a monocarboxylic acid having the general formula See Patent for Tabular Presenta- tion PS wherein R '" is a hydrocarbon group with 5-23 carbon atoms, the acid as being in an amount to increase the yield and/or the selec- tivity of the monoester in the flotation of alkaline earth metal-containing oxide and salt type minerals, such as apatite, fluorspar, calcite, baryte, scheelite, dolomite, and magnesite.

5133506

APPARATUS FOR GRINDING MINERAL PRODUCTS

Jan O Bogen, Kvicksund, Sweden assigned to Sala International AB

The invention relates to apparatus for grinding mineral products and similar hard materials with the aid of a grinding medium agitated by a pin- equipped rotor,and is characterized in that the pins are manufactured of cemented metal car- bide.

5139663

DISCHARGE VALVE FOR DISSOLVED AIR FLOTATION

William Maples assigned to Microlift Systems Limited Partnership

A self-cleaning valve for discharge of a pre- ssurized dissolved air flotation aqueous treat- ment liquid from a high pressure reservoir to a low pressure body of liquid to be treated is pro- vided. The valve includes a discharge head body adapted to be attached to a conduit supplied with pressurized treatment liquid which is pro- vided with a central opening for discharge of a treatment liquid. The opening is controllable by means of a reciprocable cap positioned to reciprocate from a position whereon it restricts flow of liquid through the opening to a position wherein flow in unrestricted. The cap is attached to a reciprocable piston rod attached at its op- posite end to a piston that is movable within an enclosed cylinder. The cylinder is provided with a port or opening on each side of said piston into which a source of pressurized air connectable to cause movement of the piston and thus opening and closing of the valve by selectively directing the flow of said pressurized air to either side of the piston. A variable pressure regulating means can be provided to regulate the amount of flow through the valve.

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