, v G. J. BANCROFT. PROCESS 0F SEPARATING MICA FROM FELDSPAR.

APPLICATION FILED AUG-9,191?.

GEORGE J. BANCROFT, OF DENVER, COLORADO.

PROCESS OF SEPARATING MICA FROM FELDSPAR.

V Specification of Letters Patent.

Patented July 22, 1919.

Application filed August 9, 1917. Serial N o. 185,274.

To all lwhom, z't may concern:

Be it known that I, GEORGEA J. BANCRoFT, a citizen of the United States, residing at the Acity and county of Denver and State of Colorado, have invented certain new and useful Improvements in Processes of Separating Mica from Feldspar; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in theart .to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which form a part of this specication. My mvention relates to a process for separating mica from feldspar. All mica deposits the world over are mixtures of mica, feldspar and quartz. The quartz is found in large masses by itself. The mical and feldspar are more or less mixed together. The usual way of mining and treating mica is as follows:

VThe deposit is very carefully mined, involving extra mining cost, then the mica is carefully sorted out by hand and cleaned by hand, involving additional expense, then the mica is ground in special grinding Inachines. Some deposits produce sheet mica to the extent of 5% or 10% of the total yield, but inasmuch Vas the improvements herein considered have nothing to do With the handling of sheet mica, I will consider a case where all of the mica is gro-und to a bran or Hour condition.

Clean mica. is extremely diflicult to grind. It is like grinding well greased iron washers. It is tough, and Well lubricated. It will be seen that every step of this process (which is the lcustomary one) is very costly. Furthermore, the grinding of dry mica is attended by very heavy mortality on the part of the Workmen, the dust being very injurious.

My method simplifies and cheapens each step of the processand there is no dust. In the first place, the feldspar and mica are mined and shipped to the mill together. This greatly cheapens the mining, and fur thermore, conserves the mineral resources of the country, because all of the deposit can be Worked, instead of what appears to be the richer part of it. The feldspar and mica are then ground together Wet. The sharp spar grinds the mica so that the two ma-l IVilley type and the lines to another. ySeveral tables may be used if the volume is sufi'b cient to require increased table capacity. Any type of reciprocating table can be used, such as lVilfley, Cammett or Card. Whatever table is used is not used as a concen trator, although all these tables are concentrating tables. The specific gravity of the feldspar and mica is nearly the same, feldspar being 2.6 and mical 2.8. Yet, I make a concentrate of the lighter n'iyaterial and tailings of theheavier material. This is done Vby taking advantage of the Hake-like fracture of the mica and the granular fracture of the feldspar. The table is converted into a washer rather than a concentrator. Different tables require different adjustments, but in general the following procedure Will give the desired result. An excess of water is used. The table is inclined edgewise or transversely of its length, more than for concentrating purposes, while endwise or longitudinally it is inclined to a less degree than for concentration.

The Card table has proven 'better than others for this purpose. headingsare normally in excess of the mica or tailings, which is contrary to the ordinary concentrating procedure. The Card table has al large discharge area for headings and consequently, Works more satisfactorily than other tables. After leaving the tables the headings or feldspar and the tailings or mica go to settling tanks or `filter presses, or both.

The mica is sorted by settling or screened With screens into various commercial sizes. The finest size may be recovered by a filter press in some cases to better advantage than by settling. The various sizes of mica are then dried and sacked and are ready for the market.

In passing over the tables, the iron and other heavy elements come out in a streak by themselves in spite of the fact that the table is set for washing instead of concentrating. hese concentrates of iron and heavy materia-ls are, of co-urse, very dirty because the tables are not set for concentrat- The feldspar or ing purposes. However, the main point in this process is to get rid of them and leave the feldspar free and clear of iron. This is nipulation or machinery.

readily accomplished Without additional ma- The purified feld-` spar is then dried and ground in a flintlined tube mill with flint pebbles to a neness about one hundred mesh suitable for the trade, being mainly used` by porcelain and pottery makers. The heavy concentrates may contain enough rare metal to render them valuable. T-itanium is a lcommon associate of mica deposits, While gold, platinum, nickel and other valuable metals are not unknown.

In the accompanying drawing I have diagrammatically illustrated suitable' apparatus for practising the process as heretofore outlined. Thisy dra-Wing which consists of a single view as all the various apparatuses 'are assumed to be connected in operative'relation, will now bedescribed.

Let the numeral 5- designate a crusher to Which the mica and feldspar are delivered in the first instance. The crushed material passes from tlie Crusher to a ball mill or stamp 6 Where it is reduced to the desired inenes's and from which it passes to a hydraulic sizer or classifier 7 .from which the fines go to a concentrating table 8 and the coarse grade to a similar table 9. From both of these tables .the tailings constituting the mica portion of the product may pass to a settling tank 10, thence to a filter 12, a drier 13 and trommel screens 14 the finished product finally passing to bins 15; While from the concentrating tables the product from the concentrates end (except the iron) which constitutes the feldspar may pass to a drier 16, thence to a tube mill 17 and next to a lmagnetic separator 18, Where any remaining traces of iron are removed, the finished feldspar finally passing to a bin 19.

Lames@ It is believed that this `drawing will be sufcient for the urpose, since any suitable apparatus or ot er series of apparatuses -which will produce the required function may be employed.

Having thus described my invention, what I claim is:

1. A process which comprises grinding together mica and an insoluble abrasive matetogether mica and an insoluble abrasive ma-` terial, lighter than the mica, and separating the mica by Washing the material on a table so that the mica is washed from the abrasive material due to the flakycharacteristics of the mica.

3. A process, which comprises grinding together mica and an insoluble abrasive material lighter than the mica in the form in which these materials are found together when mined, and separating the y mica by Washing the ground material on a table so that the mica is Washed out from the lighter abrasive material due to the flaky characteristics of the mica.

4. A process which comprises grinding together mica and an insoluble abrasive material, such as quartz-and'feldspar, and separating the mica from' the abrasive by washing the material on a table so that the mica is washed from the abrasive material due to the flaky characteristics of the mica.

In testimony whereof I affix my signature.

' GEORGE J. BANCROFT.