US1443607A - Launder - Google Patents

Description

C. ALLEN.

Jan. 30, 1923.

LAUNDER.

FILED JUNE 29.1921.

Patented Jan. 30, 1923.

UNITED STATES CHARLES ALLEN, OF EL PASO, TEXAS.

LAUNDER.

Application filed June 29, 1921. Serial No. 481,308.

To all whom z'tmay concern:

Be it known that! I, CHARLES ALLEN, a citizen of the United States, residin at El Paso, in. the county of El Paso and tate of Texas, have invented new and useful Improvements in Launders, of which the following is a specification.

This invention relates to a launder de-' vice for conveying dewatered or partially .dewatered ores, sands, and the like, and has for its object to divert a stream whenever it exceeds a certain predetermined degree of dilution.

In certain types of classifiers, the water entering the receptacle with the feed stream, in excess of that discharged with the classified or dewatered material, over-flows the top of the receptacle. The device functions satisfactorily only as long as the solids settling in the receptacle are in quantity just suflicient to supply the outflow through the orifice provided for their discharge, after a bed of: solids have settled in the receptacle. If the solids settle in excess of the discharging capacity of the orifice the receptacle fills with settled solids when particles that should be discharged through the orifice pass away with the overflow, and if less solids settle in the receptacle than are discharging through the orifice, as soon as the settled solids over the orifice are discharged, a flood of practically the unclassified feed stream is discharged through the orifice, the volume so discharged being several times that of the settled sand previously discharged in the same period of time.

When a body of settledsand overlies an orifice the friction of the particles among themselves is such that the sand outflows through the orifice with very much less velocity than the velocity of issuance of a liquid under the same velocity head. In tests made with a receptacle approximating four feet in depth from orifice to overflow lip, theorifice being one inch in diameter,

the settled solids discharged through the orifice with a velocity of approximately twenty inches per second, whereas, under a like velocity head water will issue with a theoretical velocity of approximately two hundred inches per second. Hence the water discharge would be ten times the volume of the san i In the wet milling of ores, washing of sand and the, like both the relative proportion of water to solids and the relative proportion of the difl'erent mesh size particles to each other vary largely. Among thecauses for these variations is the mechanical condition of the solids fed to the pulverizing machine. It is sometimes nearly allcoarse material which is pulverized comparatively slowly, at other times there is a large percentage of fine and very fine material which passes through the pulverizer much more rapidly. Such variation in the character of the solids fed is practically unavoidable for segregation takes place inthe bins from which the head is drawn.

The total quantity of solids in the pulverizer discharge may remain normal and there be great percentage differences from the normal in the relative mesh size of the particles. In a cone classifier of the type with which the present invention is concerned, every such variation increases or diminishes the quantity of solids that should pass to the bottom discharge orifice.

' The foregoing are some of the principal reasons why classifiers and dewaterers of the type shown will with more or less frequency discharge the practically unchanged feed stream. The damage of such erratic dis charge is far-reaching in practice for it is not a question of simply stopping the flow and then immediately resuming normal operations. In many cases it means hours of sub-normal operation.

For example: where a cone classifier is used 'inclosed'circuit with a ball mill, it will be evident that if no provision were made to prevent it, when the classifier breaks loose (as previously described) and discharges a large volume of the unclassified feed stream, the whole of the dilute stream would pass into the ball mill. It is seldom that a ball or tube mill will pulverize with high efficiency when the feed stream to it contains more than 40% water (40% water and solids). The dilute discharge from the classifier would almost empty the ity concentrators, flotation cells, 01- the like, then when the classifier breaks loosethe flood of water would put them out of commission, causing losses of both values and time.

When a ewatering device is used to build tock piles or to fill bins, then when the material breaks loose the discharge not only adds water to the previously dewatered material. but also contaminates the material in the pile, or the bin by adding to it the ma terial discharged with the water.

In and by the present invention I provide a 'launder device whereby material of a cer tain dilution will fall through a gap in the bottom of the launder, and whenever the material reaches a predetermined degree of dilution it will pass the gap and be diverted elsewhere.

In the accompanying drawings Fig. 1. shows a classifier arranged in closed circuit with a ball mill and having a launder device interposed between the classifier and ball mill, such launder device being provided with a gap in accordance with my invention.

Fig. 2. shows a modified form of the gap of the launder.

Fig. 3. shows a further modification of the gap of the launder wherein provision 18 made for adjusting the width of the gap.

Fig. 4. shows a still further modification of the same wherein the gap of the launder is provided with a false bottom, the angle of whlch may be adjusted.

Referring in detail to the accompanying drawings, I show a cone classifier 10 having an overfiow rim at 11, emptying into a discharge launder 12. The classifier has a dis charge orifice 13 at its apex for supplying esired point or receptacle, such as a ball mill 14. A feed stream is supplied to the classifier through the launder 15. 7

Instead of directly discharging the classified material into the ballmill, I interpose a special form of launder 16, having an upper part 17 and a lower part 18 with an intermediate gap 19. The upper part 17 has a declination of between two and three inches to a foot of length for purposes here- I inafter to be made clear. The gap 19 communicates with the trough 20 which empties into theball mill or other receptacle.

In Fig. 2, I show a modification of the launder 16, wherein the upper part1? is provided, at its lower end, with an upturned port1on'2l. In Fig. 3, I show a plate. 22 slidably mounted on the launder 16 for the purpose of adjusting the width of the gap 19. In Fig. 4, I show a false bottom 23 held 1n place on the upper portion 17 by means of a screw 24, or otherwise, and provide means, such as a wedge 25 for adjusting the inclination of the false bottom 24.

Settled quartz sand in water discharged through an orifice in the bottom of a receptacle in which a bed of settled sand is main tained over the orifice. is discharged through the orifice-accompanied by approximately 30% water (30% water and sand by weight). Such material will seldom flow down a launder having a fall of two inches per foot of length, and will usually flow down a launder having a fallof three inches per foot, whereas, if the same sand be diluted to several parts of water to one of and it will flow down the same launder with a high velocity, and on this fact is based the functioning of-the launder gap.

Referring to Fig. 1when a normal discharge is issuing from 13 (approximately 70% solids and 30% water) the discharge flows slowly down the inclined plane formed by the launder part 17, and falls ofi the .upper edge of the gap into the trough 20,

down which it flows to the ball mill. Due to the inclination of part 16, the velocity of the flow is such that it cannot jump the gap 19 and flow down the part 18. Assume now that the sand settling in 10 has so diminished that the cone is emptied of its normal bed of settled solids over the orifice 13. The latter will then discharge a. large volume feed stream. As hereinbefore stated the volume discharged under these conditions will approximate ten when the classifier is functioning normally, and the increase is almost wholly water. A stream of this composition and volume will flow down a launder having a fall of from two to three inches to the foot with a very high velocity and a very large portion of the stream will jum the gap in the bottom of the launder. l ith a step down as shown by Fig. 1, or an upward inclination to the bottom of the launder above thegap as shown by Fig. 2, or with the false bottom of Fig. 4, the entire stream may be caused to pass over the gap. I Anything that increases the velocity of the flow down they launder above the gap 19 increases the tendency of the stream to jump the gap, and an increase in either the volume or the dilution, or both, increases the velocity and both are effective on the velocity the instant that the last of the sand bed normally maintained in the classifier is dischargedthrough the orifice.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. The method of conducting material in a 'dewatered or partially dewatered state to a place of use so as. to divert substantially all the material when it exceeds the desired degree of dilution which consists of flowing the material down an inclined launder having a gap .in its bottom through which the of the practically unclassified times that of the discharge material is discharged when it is of a prethe material to jump the gap when it exceeds the predetermined degree of dilution.

2. The combination with a feeder for discharging material in a. dewatered or partially dewatereclstatemf an inclined launder to receive the discharged material, said launder having a gap in its bottom through which the material passes when it is of a predetermined degree of dilution, a branch launder communicating with said gap to conduct the material to-the place *of'use-,-'said first mentioned launder being. at such an inclination and the size of the gap being of such width as to cause substantially all the material to jump the gap when it exceeds the predetermined degree of dilution.

3. The combination set forth in claim 2 including means for varying the relation' between the inclination of the launder and the size of the gap whereby to permit material of varying degree of dilution to pass through the gap and enter the branch laun der.

4. The combination with a receptacle for discharging dewatered or partially dewatered ores, sand and the like, of means to direct the discharged material to a place of use and means automatically responsive to changes in the fluidity of'the stream to divert the same when it falls below a predetermined degree of dilution. V

' CHARLES ALLEN.

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