US2498111A

US2498111A - Method of obtaining mica

Info

Publication number: US2498111A
Application number: US633074A
Authority: US
Inventors: William M Mattson
Original assignee: CONCORD MICA CORP
Current assignee: CONCORD MICA Corp
Priority date: 1945-12-06
Filing date: 1945-12-06
Publication date: 1950-02-21
Anticipated expiration: 1967-02-21

Description

Feb. 21, 1950 w. TTso 2,498,111

METHOD OF OBTAINING MICA Filed Dec. 6, 1945 Patented Feb. 21, 1 950 UNITED STATES PATENT OFFICE METHOD OF OBTAINING MICA William M. Mattson, Concord, N. 11., assignor to Concord Mica Corporation, Concord, N. H., a corporation of New Hampshire Application December 6, 1945, Serial No. 633,074

2 Claims. 1

The method pertains to an improvement in methods heretofore employed for obtaining mica by wet grinding of the scrap from which the mica is obtained and especially a method employing a centrifuge for dehydration.

Among the objects of the invention are:

To increase the amount of mica recovered from any treated batch of material, and with as little waste as possible.

To conserve in the use of water; not by using less water but by saving the water that has been used.

The method entails various steps which can best be understood in the light of the apparatus that is employed for practicing them, and which apparatus. for the most part diagrammatically illustrated, is shown in the drawings, inwhich Fig. 1 is a plan of the apparatus used in practicing the method.

Referring to the drawings, l represents one or more so-called grinding or delaminating mills, of a type like those previously employed, and with interior mechanism (not shown) acting upon the contained mass in the mill in the presence of water to delaminate or split the mica particles.

The action of the grinding mill is not to destroy the laminal structure of the mica but is a delaminating action, this by an impact or kneading action and friction of one piece on another, thereby reducing the mice, to minute plates or flakes of assorted diameters, some coarse and some fine, with a maximum thickness for each plate or flake of from one to two microns.

The operation effected by the grinding mills is a more or less protracted action on the completion of which there is obtained a mass of mica which is flushed from the grinding mill by a further addition of water in which the mica lies in such suspension that it may be piped for fur ther processing. There is also some considerable foreign matter which is removed by any suitable practice previously employed.

From the grinding mill, or mills, the water in which lie suspended the particles or flakes of mica, is conveyed through a pipe, or pipes, 2 to an agitating tank, or tanks, 3. Two or more of these tanks are preferably employed connected with one another in order that an ample supply of material to be dewatered may be maintained at all times, and especially during the processing of new material introduced into the grind-- ing mills, the dewatering of ground material going onduring such period. Each of the tanks has associated with it a power controlled agitating mechanism (as shown) which keeps the conwithdrawn for dewatering.

The dewatering is effected by a centrifugal machine into which the content of one of the agitating tanks is directed through a pipe 5. This action is effected by means of a pump 6 and the pipe is also fitted with any suitable cutoff valve 1.

The centrifuge is one of common type having a rotated basket 8 into the interior of which the pipe 5 extends for discharging the matter passing through it. The action of the centrifuge is to throw by centrifugal force against its sides the mica particles introduced into it, which particles build up or accumulate along and within the side of the basketin a dewatered mass, and the waste water is thrown out through the open top of the basket.

While the centrifuge is most economical and efficient in recovering the coarser and larger mica plates or flakes which carry with them a considerable quantity of the finer and smaller mica flakes, yet I have discovered that there remains a large percentage of the finer and smaller mica flakes not taken up by the heavier particles, and which are so small and lacking in weight as to be incapable of being thrown laterally in their initial passage through the machine as the heavier particles are thrown into the dewatered mass but will remain suspended in the waste or extracted water and accordingly will pass out through the top of the basket in this water. In consequence, according to the present method, the waste water expelled from the centrifuge to the top of its basket is collected by entry into a chamber 9 built around the basket and thence directed through pipes Ill into settling tanks ll. Passage through these pipes for any and all the settling tanks iscontrolled by valves I2. I prefer to employ a number of these settling tanks with total capacity suflicient to receive and hold substantially all water introduced into the grinding mills that has been previously used for effecting the grinding operation and for flushing these mills.

The mice, that has accumulated within the basket of the centrifuge is removed after closing the valve in the pipe 5 leading from the agitating tank from which the feed is madeto the centrifuge. Thereupon the mica accumulated within the basket of the machine is removed in the usual manner by shovels (not shown) which form a part of the machine.

The matter introduced into the settling tanks is allowed to settle, leaving an accumulated mass of mica particles, or sludge, at the bottom and an accumulation of water above, though this accumulated water may have some fine mica particles within it.

The settling or sludge at the bottom is pumped back into one of the agitating tanks, preferably the one from which the feed is directed to the centrifugal machine. The accumulated mica sludge is thus directed into the agitating tank in order that the fine mica particles in the sludge may be taken up by the heavier mica particles 7 in the agitating tank and be carried to the centrifugal machine and be thrown off by centrifugal force. In this connection full advantage is taken of the excellent adhesive qualities of the fine mica flakes, which are suspended in the waste water, or sludge, to adhere to the heavier particles in the agitating tank. Mica flakes have an affinity or attraction for each other and will stick or cleave together so that the heavier mica particles in the agitating tank will take up and carry the finer particles, thus making possible the continuous process of eventually recovering all the fine mica plate or flakes obtained by the initial grinding, and formerly wasted in their passage through the centrifugal dewatering machine.

The accumulation of water in the settling tanks left after the settling of the mica flakes is pumped back into the grinding mills to be used both for the watering of fresh stock and for flushing these mills as occasion requires. Water from the settling tanks may also be pumped back into the agitating tank from which the feed is made to the centrifuge if and when this tank requires an extra supply of water.

Any suitable means may be provided for disposing of the contents of the settling tanks as previously referred to. In practice a pipe section 13 leads from that bottom portion of each of the settling tanks which contains the sludge. The passage through this pipe section is controlled by a valve 14. Another pipe section l5 leads from that portion of each of the settling tanks which contains the water content lying above the settling. The passage through this pipe section is controlled by a valve l6. Both the pipe sections I3 and I5 connect with a common pipe ll leading to the inlet of a pump l8. Extending from the outlet end of this pump is a pipe section l9 connecting to a pipe section having branches 20 and 2| extending in different directions, one the pipe section 20 extending to the agitating tank 3 with a valve 22 for controlling the discharge into this tank, and the other branch 2| extending to connect with the grinding mills through pipe s:ctions 23. Passage through the branch section 2| is controlled by a valve 24 and the passage to each of the grinding mills through the pipe section 23 is controlled by a valve 25. Obviously by the opening and closure of certain of those valves the sludge in any or all of the receiving tanks may be pumped into the agitating tank, and by the opening and closure of certain other of said valves the water in any or all of the settling tanks may be pumped into any or all of the grinding mills, or into the agitating tank, as occasion may require.

After dewatering by the centrifuge all recovered mica is dried and screened in the usual manher.

I claim:

1. In the process of obtaining mica from micaceous stock by wet grinding and in which a centrifuge is employed to which water with micaceous matter is delivered for purpose of dehydration and from which centrifuge water containing small particles of micaceous matter unhydrated by the centrifuge is discharged, the steps of recovering the micaceous matter in the water so discharged which comprises collecting the water discharged from the centrifuge containing the small particles of micaceous matter as aforesaid and allowing such matter to settle in the water so collected to form a sludge, subjecting this sludge by suspension in water to the presence of larger ground particles of micaceous matter capable of dehydration in a centrifuge and agitating whereby the larger particles will take up the smaller particles of the sludge and afterwards delivering the lar er particles of micaceous matter bearing the smaller particles obtained from the sludge to the centrifuge for purpose of dehydration.

2. In the obtaining of mica from micaceous stock employing among other elements a grinding mill for reducing the stock in the presence of water and a centrifuge to which water with micaceous matter is delivered for purpose of dehydration and from which centrifuge water containing small particles of unhydrated micaceous matter is discharged, the steps of recovering the water and small particles of micaceous matter in it discharged from the centrifuge which comprises collecting the water discharged from the centrifuge containing the small particles of micaceous matter as aforesaid and allowing such matter to settle in the water so collected to form a sludge with supernated water above the sludge, returning the supernated water to the grinding mill and subjecting the sludge by suspension in water to the presence of larger ground particles of micaceous matter capable of dehydration in a centrifuge and agitating whereby the larger particles will take up the smaller particles of the sludge and afterwards delivering the larger particles of micaceous matter bearing the smaller particles obtained from the sludge to the cen trifuge for purpose of dehydration.

WILLLIAM M. MA'I'ISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Atwood June 11, 1940 OTHER REFERENCES Number