US3795807A

US3795807A - Pneumatic conveying system for transferring slurry samples to an analyzer

Info

Publication number: US3795807A
Application number: US00296542A
Authority: US
Inventors: G Johnson; L Matthews
Original assignee: Anaconda Co
Current assignee: Anaconda Co; Atlantic Richfield Co
Priority date: 1972-10-11
Filing date: 1972-10-11
Publication date: 1974-03-05
Anticipated expiration: 1991-03-05

Abstract

A pneumatic slurry transfer system for intermittently transferring a slurry sample from a pressure tank, through a conduit and to a discharge tank for subsequent chemical analysis whereby a liquid medium is initially introduced into the conduit and confined therein and whereby the slurry sample is forced by gas pressure to contact the liquid medium and slowly permeate thereinto while the slurry and liquid medium are simultaneously transported through the conduit to the discharge tank by the gas pressure.

Description

United States Patent m1 Johnson et al. P Mar. 5, 1974 [54] PNEUMATIC CONVEYING SYSTEM FOR 3,443,092 5/1969 Carr-Brion et al 250/51.5 TRANSFERRING SLURRY SAMPLES o AN 3,469,095 9/ i969 Starnes 250/43.5

ANALYZER [75] Inventors: Gary Jahnson; Larry Primary Examiner-William F. Lindquist Matthews, both of Tucson, Am.

{73] Assignee: The Anaconda Company, New

York, NY. 22 Filed: on. 11, 1972 [571 ABSTRACT [21] Appl 296542 A pneumatic slurry transfer system for intermittently Related U.S. Application Data transferring a slurry sample from a pressure tank, [63] cgminuafion 0Q No. 82842, 16 1970 through a conduit and to a discharge tank for subse- QBJ EEEQI "1 w T quent chemical analysis whereby a liquid medium is initially introduced into the conduit and confined [52] U.S. Cl 250/273, 250/277, 250/343 therein and w r y h l rry sampl is forcedby gas [51] Int. Cl. G0ln 23/22 pressure to ta th iquid m dium and slowly per- [58] Field'of Search 250/43,5 R, 51,5; 302/14, 20 meate thereinto while the slurry and liquid medium are simultaneously transported through the conduit to [56] References Cited the discharge tank by the gas pressure.

UNITED STATES PATENTS 3,239,849 3/1966 Liljendahl .L 302/14 X 10 Claims, 3 Drawing Figures SIRS/9M 1 390444) @775? 2| Pia w ale/7e45 //-/LE7' [Kw/4' Sara/army C0775? 27 g as 7'0 s4 F l Mme/inlay H45 EPl E/Yf M47272 M4:

0 x/ I 06 82:: [A0 2e X-EA -28 A/vmvZE/Q PATENTED 5 SIEEIIUFZ PATENIEDKAR 51914 5.795.807

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2 or 2 INVENTORS PNEUMATIC CONVEYING SYSTEM FOR TRANSFERRING SLURRY SAMPLES TO AN ANALYZER REFERENCE TO RELATED APPLICATIONS This application is a continuation of application Ser. No. 89,842, filed Nov. 16, 1970, now abandoned.

BACKGROUND OF THE INVENTION Conventional metallurgical operations for concentrating and recovering metal values from raw ore material involve initially treating the raw ore material in order to form a raw ore slurry. Raw ore material in this physical form may be more effectively treated to recover the metal values. During these conventional operations it is desirable to analyze the slurry at various points along the concentrating circuit to determine the concentrations of one or more of its chemical components. This is ordinarily accomplished by removing a sampleof the slurry from desired points along the moving slurry circuit stream and directing the slurry samples to 'an analyzer, such as an X-ray analyzer, where the measurements are made.

Many systems have been developed in the past for removing slurry samples from a moving main slurry stream in order to chemically analyzethe stream. One such system includes a liquid sump pump which continuously removes slurry sample from a moving slurry circuit stream and continuously pumps the slurry sample to a screen inorder to remove any foreign matter contained therein. The continuously flowing slurry sample then flows by gravity through a gang sampler and a selection table which acts to divide the continuously moving slurry sample into smaller portions for delivery to a head tank and finally to an analyzer.

Rather than transferring a large continuous volume of slurry sample from place to place by gravity or by the use of conventional mechanical liquid pumps, pneumatic systems may be utilized whereby relatively small charges of slurry samples are intermittently transferred through a conveying line by air pressure. However, as the slurry samples flow under such air pressure to an analyzer, it has been found that the slurry classifies itself as each sample moves through the conveying line. Classification is due to the tendency of the heavier slurry particles present near the front of the slurry sample to be moved more readily by the air pressure toward the very front end of the moving slurry sample. The gradual accumulation of these heavier particles in the above region of the slurry sample eventually forms a plug which clogs the conveying line.

SUMMARY OF THE INVENTION ported through the conduit to the discharge tank by the gas pressure.

This system provides an efficient and effective way of transferring slurry samples for-analysis and, at the same time, eliminates the need for using a system which requires mechanical pumps and other complex mechanical equipment which are more likely to break down by wear when they are subjected to continual use. Further,

by using the system of this invention, it ispossible to eliminate the classifying effect that occurs when surry samples are intermittently forced through a conveying line by gas under pressure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the overall system of this invention;

FIG. 2 is a detailed side view partially in section of DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a moving main stream of slurry from which slurry samples are periodically removed for chemical analysis. The slurry samples are diverted from the main slurry stream by means of a cutter assembly comprising a primary cutter l and a secondary cutter 2, arranged in series, The primary cutter l is constructed to continually remove or divert a portion of the slurry from the main slurry stream and direct the diverted portion to the secondary cutter 2. The secondary cutter 2 takes the slurry samples from the diverted portion and directs these slurry samples to a surge tank 3. The slurry samples, that are rejected by the secondary cutter 2, are returned to the main slurry stream.

The particular amount of slurry that is continuously removed from the main slurry stream by the primary cutter 1 and the particular amount of slurry that is periodically diverted by the secondary cutter 2 is not critical to the operation of this invention; however, it is desirable that the particular amounts be such that the rate of the slurry sample emanating from the secondary cutter 2 should be approximately 1 to 4 gallons every 30 minutes.

The sample slurry, transferred to the surge tank 3, first falls by gravity through a screen 4 which is positioned within the upper portion of the surge'tank 3 in order to collect any foreign matter such as enlarged metal particles, chunks of wood, or any oversize slurry particles. The oversize particles are removed from the surge tank 3 when the'screen 4 becomes plugged by passage through overflow outlet 5. After passing through the screen 4, the slurry sample falls into the main portion of the surge tank 3. The slurry sample then passes by gravity through a feed valve 7, located at the lower end of the surge tank 3, and into a cylindrical pressure tank 8.

The pressure tank 8 comprises an upright upper section 10 and a conical bottom section 11 and has a working capacity of about 5 gallons. The upper section 10'is preferably plastic lined. The upper end of the upper section 10 communicates with the surge tank 3 through a conduit 9 and also carries a water inlet 12 and an associated water inlet valve 13 together with an air inlet 14 and an associated air inlet valve 15.

The conical bottom section 11 of the pressure tank 8 is provided with a slurry outlet 16 and a slurry outlet valve 17 both positioned at its lower end.

The slurry sample in the pressure tank 8 is kept in constant motion by means of a mechanical agitator 18 which is adapted to extend and continuously rotate therein.

An elongated slurry transfer conduit 20 is arranged to provide communication between the slurry outlet valve 17 of the pressure tank 8 and a plant sampler 21.

A portion of the transfer conduit 20 along its axis is U-shaped in configuration. Further this portion, indi cated generally by 23, is positioned immediately adjacent to the slurry outlet 16 of the pressure tank 8 so as to provide direct and immediate communication between the pressure tank 8 and the portion 23. The conduit 20 preferably has an insidediameter of about /2 inch and may have a length up to about 500 feet.

The pressure tank 8 is operated by simultaneously closing the normally open feed valve 7, and opening normally closed slurry outlet valve 17 and air inlet valve to allow the contents of the pressure tank 8 to be forced by air pressure through conduit 20. After the slurry has been removed, normally closed water inlet valve 13 is opened for about 1 second thereby flushing any accumulated materials from the pressure tank 8 and into conduit 20. After the flush water and contained slurry have been transported through conduit 20, the air inlet valve 15 is closed thus allowing pressure tank 8 to be decompressed. The water inlet valve 13 is subsequently opened again for about one second to add enough water into the pressure tank 8 in order to completely fill the U-shaped portion 23. The water inlet valve 13 and the slurry outlet valve 17 are then closed and the feed valve 7 is opened and the slurry sample is thereby allowed to enter the pressure tank 8. When the pressure tank 8 has collected its required slurry sample of l to 4 gallons, the feed valve 7 is shut off and the air inlet valve 15 and the slurry outlet valve 17 are opened. With the feed valve 7 now in an offposition, the slurry sample is allowed to accumulate in the surge tank 3 preparatory to the transfer of this slurry sample to the pressure tank 8 at a later time.

The air entering the pressure tank 8 pressurizes the slurry sample and thereby forces it against the water that is confined in the U-shaped portion 23 of the conduit 20. Further the air pressure will move the previous confined water and the slurry sample through the entire length of the conduit 20 to the plant sampler 21.

It has been found that, since the water initially present and confined in the U-shaped portion 23 has a density less than the slurry sample, the heavier particles of the slurry sample present near the front of the column of the slurry sample moving through the conduit 20 will slowly permeate into the water and become suspended therein as the slurry sample is moved through the conduit 20 to the plant sampler 21 by the air pressure. Since such heavy particles are thereby suspended and remain suspended within the water as the slurry sample is being conveyed through conduit 20, the undesirable clogging effect, aforementioned, will not occur.

' It is to be understood that water is not the only liquid medium that may be used to accomplish the above effect. Other liquid mediums may be used as long as the slurry is capable of permeating thereinto. Under these conditions the heavier particles of the slurry will permeate into the liquid medium as the slurry moves through the conduit 20. Further, the exact amount of liquid medium that is used or the exact dimensions of the U-shaped portion 23 of the conduit 20 is not critical since the particular values chosen depend upon the distance that the slurry sample will be conveyed and the size of the particles in the slurry. However, in order to in length, the desired amount of liquid medium that would be usedwould be a volume of about 7 cubic inches.

The plant sampler 21 periodically removes a portion of the slurry sample and redirects this portion through a sampler outlet 24 for an independent laboratory examination. The portion of the slurry sample that is not removed through the sampler outlet 24 flows by gravity through a feed inlet valve 25 and into a cylindrical constant head or discharge tank 26 through an inlet 27 located at its upper end. This constant head tank is constructed to subsequently transfer the slurry sample at a constant rate to the X-ray analyzer 28 since the X-ray analyzer will more accurately measure the chemical characteristics of the slurry sample under this condition.

The constant head tank 26 comprises an upper section 30 and a lower funnel section 31. The upper section 30 is closed at its upper end while the upper end of the funnel section 31 is open to the atmosphere. The upper section 30 of the constant head tank 26 is preferably plastic lined, has a rather small interior diameter, preferably about 10 inches, and has a working capacity of about 5 gallons. The top of the upper section 30 carries both a vent valve 32 for venting the interior of the upper section 30 to the atmosphere and an agitator 33 which extends and continuously rotates within the.

upper section 30. Also the top of the upper section 30 is provided with a water inlet 34 and an associated water inlet valve 35 for supplying an amount of wash waterto the interior of the constant head tank 26.

The lower end of the plastic lined upper section 30 has a discharge opening 36 and a downwardly extending cylindrical lip 37 which is positioned to extend within the funnel section 31. Associated with the discharge outlet 36 there is provided a butterfly valve 38 which is actuated by an air cylinder, generally indicated by 40, that is secured to the side of the upper section 30 of the constant head tank 26.

The funnel section 31 is provided with an' outlet 41 at its low end and has a stabilizing funnel 42 concentrically positioned therewithin. The stabilizing funnel 42 is spaced from both the funnel section 31 and the cylindrical lip 37.

The outlet 41 of the funnel section 31 is connected to a transfer conduit 43 which is adapted to convey the contents of the constant head tank 26 to the X-ray analyzer 28. After the slurry sample is analyzed it is returned to the main slurry stream through conduit 44.

Before any slurry sample is introduced into the constant head tank 26 it is washed clean with water by closing the feed inlet valve 25 and opening the water inlet valve 35 to thereby allow wash water to flow into the upper section through the water inlet 34. The constant head tank 26 is now ready for receiving the slurry sample from the plant sampler 21 and for transferring at a constant rate the slurry sample to the X-ray analyzer 28. The feed inlet valve 25 and the vent valve 32 are then both opened and the butterfly valve 38 is closed. After the slurry sample has been transferred into the upper section 30 of the constant head tank 26, the vent valve 32 and the feed valve 25 are closed. The butterfly valve 38 is then opened and the slurry sample is thereby allowed to flow through both the discharge opening 36 and the cylindrical lip 37 to fill the funnel section 31. When the level in the funnel section 31 rises to the level of the lower end of the cylindrical lip 37, the slurry sample will stop flowing into the funnel section 31. The entire constant head tank 26 is thereby completely sealed with the upper section 30 under a negative pressure which counteracts the weight of the slurry sample therein. As the slurry sample in the funnel section 31 drains by gravity into the transfer conduit 43, the upper level of the slurry sample drops below the level of the lower end of the cylindrical lip 37. Atmospheric air is thereby allowed to enter the upper section 30 through the discharge outlet 36 and more slurry sample is, accordingly, released to flow into the funnel section 31. The flow of slurry sample into the funnel section 31 will stop again when the upper level of slurry sample in the funnel section 31 rises to the level of the lower end of the cylindrical lip 37 This procedure repeats itself until the constant head tank 26 is empty. After theslurry sample has been removed by gravity from the constant head tank 26, the washing cycle is repeated in order to prepare the constant head tank 26 for receiving additional slurry sample.

Having described the invention with particular reference to the preferred forms thereof, it will be obvious to those skilled in the art to which this invention pertains, after understanding the invention, that various changes and modifications may be made therein without departing from the spirit and scope of the invention, as defined in the claims appended hereto.

I claim:

1. A method of pneumatically transferring a slurry sample from a pressure tank to a discharge tank through an intermediate connecting conduit comprising introducing liquid medium into the conduit, confm-- ing the liquid medium in sufficient volume within the conduit so as to fill a length thereof adjacent the pressure tank, thereafter subjecting the slurry sample in the pressure tank to a gas pressure greater than atmosphere pressure, passing said sample into said conduit to contact the liquid medium, moving the slurry sample and the liquid medium simultaneously in one continuous movement through the conduit'to the discharge tank by said gas pressure while the slurry sample permeates into the liquid medium volume, discharging the slurry sample from the discharge tank and subsequently analyzing the characteristics of the slurry sample.

2. The method of claim I wherein the liquid medium is water.

3. The method of claim 1 wherein the gas is air.

4. The method of claim 1 wherein the chemical characteristics of the slurry sample are analyzed.

5. The method of claim 1 wherein the slurry sample is discharged from the discharge tank at a constant rate.

6. The method of claim 1 wherein the slurry sample is removed from a continuous moving main slurry stream and transferred to the pressure tank.

7. A transfer system for pneumatically and intermittently transferring a slurry sample comprising a pressure tank for holding a slurry sample under pressure, said pressure tank having a slurry sample outlet, a discharge tank for receiving the slurry samplefrom the pressure tank, said discharge tank having a slurry sample inlet, conduit means connecting the slurry sample outlet and the slurry sample inlet for communicating the slurry sample therebetween, means for supplying liquid medium to the conduit, means in said conduit for confining the liquid medium in sufficient volume to fill a portion of the conduit immediately adjacent the slurry sample outlet of the pressure tank, means for supplying gas under pressure greater than atmospheric pressure to said pressure tank to force the slurry sample to contact the liquid medium and permeate thereinto while the slurry sample and the liquid medium are simultaneously transported in one continuous movement through the conduit to the discharge tank, said discharge tank includes a means for discharging the slurry sample at a constant rate, and an analytical apparatus positioned to receive the slurry sample from the discharge tank and adapted to chemically analyze the slurry sample.

8. The slurry sample transfer system of claim 7 including a slurry sampler cutter positioned to remove the slurry sample from a main slurry stream and thereafter transfer the slurry sample to the pressure tank.

9. The slurry sample transfer system of claim 7 wherein the analytical apparatus is an X-ray analyzer.

10. The slurry sample transfer system of claim 7 wherein the discharge tank comprises an uppersection having an outlet located at its lower end and a funnel section positioned below said upper section, said funnel sectionbeing opened to the atmosphere at its upper end and having an outlet located at its lower end and said upper section outlet extending within the open upper end of the funnel section.

Claims

1. A method of pneumatically transferring a slurry sample from a pressure tank to a discharge tank through an intermediate connecting conduit comprising introducing liquid medium into the conduit, confining the liquid medium in sufficient volume within the conduit so as to fill a length thereof adjacent the pressure tank, thereafter subjecting the slurry sample in the pressure tank to a gas pressure greater than atmosphere pressure, passing said sample into said conduit to contact the liquid medium, moving the slurry sample and the liquid medium simultaneously in one continuous movement through the conduit to the discharge tank by said gas pressure while the slurry sample permeates into the liquid medium volume, discharging the slurry sample from the discharge tank and subsequently analyzing the characteristics of the slurry sample.

2. The method of claim 1 wherein the liquid medium is water.

3. The method of claim 1 wherein the gas is air.

7. A transfer system for pneumatically and intermittently transferring a slurry sample comprising a pressure tank for holding a slurry sample under pressure, said pressure tank having a slurry sample outlet, a discharge tank for receiving the slurry sample from the pressure tank, said discharge tank having a slurry sample inlet, conduit means connecting the slurry sample outlet and the slurry sample inlet for communicating the slurry sample therebetween, means for supplying liquid medium to the conduit, means in said conduit for confining the liquid medium in sufficient volume to fill a portion of the conduit immediately adjacent the slurry sample outlet of the pressure tank, means for supplying gas under pressure greater than atmospheric pressure to said pressure tank to force the slurry sample to contact the liquid medium and permeate thereinto while the slurry sample and the liquid medium are simultaneously transported in one continuous movement through the conduit to the discharge tank, said discharge tank includes a means for discharging the slurry sample at a constant rate, and an analytical apparatus positioned to receive the slurry sample from the discharge tank and adapted to chemically analyze the slurry sample.

10. The slurry sample transfer system of claim 7 wherein the discharge tank comprises an upper section having an outlet located at its lower end and a funnel section positioned below said upper section, said funnel section being opened to the atmosphere at its upper end and having an outlet located at its lower end and said upper section outlet extending within the open upper end of the funnel section.