US2158169A - Dewatering method - Google Patents

Description

M y 1939. D. M. WRIGHT 2,158,169

DEWATERING METHOD Filed Nov. 23, 1936 lll 'lll HIIII 1M] .DdI/I d M Wnigfit INVENTOR ATTORNEY Patented May 16, 1939 UNITED STATES PATENT OFFICE DEWATERING METHOD David M. Wright,.Agricola, Fla., asslgnor to Industrial Patents Corporation, Chicago, Ill., a corporation of Delaware 1 Claim.

This invention relates to'an improved dewatering method.

In mining operations in which large quantities of the mineral values are found in pieces differ- 5 ing in size from the nonmineral constituents of the gangue, it is customary to separate the mineral values from the nonmineral values by screens.

In the Florida phosphate fields the pebble phosphate is separated from the gangue by washing apparatus employing classifiers of different types, including screens.

One of the objects of the present invention is to provide an improved dewatering method particularly adaptable to phosphate rock washers. Phosphate rock in the Florida fields is hydraulically mined, and it is, therefore, necessary to dewater the rock during the process of classification.

Dewatering is one of "the functions of the washer. It is common practice in phosphate rock mining to employ large quantities of water to carry the matrix from the pit to the washer. The material is delivered at the top of the washer,

5 and in ordinary practice first passes over a fiat screen with a slope of about 2 inches to the foot to dewater the material before it enters the logs. Screens of this type are usually about to 40 feet long.

30 The method of the present invention employs a staged screen arrangement and secures more eflicient dewatering than may be secured with a conventional dewatering screen.

The drawing is a diagrammatic side view, partly in section, showing one form of a staged screen arrangement which may be employed in the method of the present invention.

Material is delivered from the mine to the washer through pipe I, and passes over a series of three screens. 2. 3. and 4, each of which is creasin'gly less mobile; 1 each succeeding screenovercomes the tendency 20 the series."

about twelve feet long. Screen 2 is provided with a slope oftwo inches to the foot, screen 3, a slope of four inches to the foot, and screen 4; a slope of six inches to the foot.

The arrangement of screens exemplified in the drawing provides two distinct advantages in dewatering. In the first place, the stage arrangement gives a redistribution of the material when i passes from screen 2 to screen 3, and again when it passes from screen 3 to screen 4, which in redistribution aids. in dewatering.

It will be noted that the screens are mounted on aframe work 5 which also carries troughs 6. l, and 8 beneath screens 2, 3, and 4 respectively to convey water passing through the screens to 13 a common drain 9.

Since the material is progressively dewatered as itproceedsdown the slopes, it becomes in- The increased slope of of thescreens to clog, and permit surges of rock to flow over rock blocked at the lower end of the screen. It is this feature which gives the present invention the peculiar utility in dewatering minerals.

-It will be understood that one or more of the screen stages may be of the vibrating type if desired. Vibration may be imparted through eccentrics or by means of any suitable apparatus.

I claim: I o

A process'for dewatering a 'freely mobile mixture of water and a solid which during dewatering becomes increasingly less mobile which con-' sists in passing. the mixture solely under the influence of gravity, over-a series of screens in- 35 clined in opposite directions and arranged one i above the other with the inclination of the screens increasing from the first to the last of DAVID M. WRIGHT. 40

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