CA1150966A - Mineral ore analyser - Google Patents
Mineral ore analyserInfo
- Publication number
- CA1150966A CA1150966A CA000366560A CA366560A CA1150966A CA 1150966 A CA1150966 A CA 1150966A CA 000366560 A CA000366560 A CA 000366560A CA 366560 A CA366560 A CA 366560A CA 1150966 A CA1150966 A CA 1150966A
- Authority
- CA
- Canada
- Prior art keywords
- particle
- ore
- particles
- mass
- station
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
- B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
- B07C5/34—Sorting according to other particular properties
- B07C5/346—Sorting according to other particular properties according to radioactive properties
Landscapes
- Analysing Materials By The Use Of Radiation (AREA)
- Sampling And Sample Adjustment (AREA)
- Measurement Of Radiation (AREA)
Abstract
ABSTRACT
A method of and apparatus for producing data useful for the statistical analysis of ore particles to establish sorting criteria, wherein the particles are moved individually by a conveyor in succession to a plurality of measuring stations.
At each station the particle is held stationary and the appropriate measurement is made. This method enables the radioactivity of a particle to be accurately related to its mass or physical dimensions.
A method of and apparatus for producing data useful for the statistical analysis of ore particles to establish sorting criteria, wherein the particles are moved individually by a conveyor in succession to a plurality of measuring stations.
At each station the particle is held stationary and the appropriate measurement is made. This method enables the radioactivity of a particle to be accurately related to its mass or physical dimensions.
Description
llS~}~66 FIELD OF THE INVENTION
This invention relates to a method of and apparatus for analysing a sample of particulate mineral ore from an ore body.
BACKGROUND TO THE INVENTION
Conventionally, the grade of an ore body is measured by periodically removing a sample of ore from the body, crushing the sample ore and subjecting the crushed sample to chemical analysis to determine its gradé. If the grade of the ore is high enough to warrant the processing of the entire ore body all of the ore and a substantial proportion of waste material, with perhaps the exception of large particles which obviously do not contain the mineral being sought and which are removed by hand from the remainder of the ore, is processed. This method of ore analysis and processing is, in terms of recovery, efficient as a very large percentage of the sought after mineral in the ore is obtained from the ore. However, a major problem with this process is thatvast quantities of unproductive material are processed to arrive at a relatively small volume percentage of the mineral and this is achieved at considerable plant and labour cost.
In deep level gold mining the above problem has been minimised by the use of automatic sorting machines which sort graded particles of a particular size or range of sizes, into particles which have a particular characteristic, such as radio-active emission, which is related to the gold grade of the ore, from particles which do not have the characteristic or have the characteristic helow a predetermined threshold. When the ore has thus been sorted only the accept ore which is the ore having the characteristic above the threshold level is then processed resulting in a considerable saving over the previously described process in both plant utilisation and labour.
In a radiometric sorting process of this type the radiometric measurement of the ore particles is considerably influenced by parameters such as the mass, volume and shape of the particles. For example, the radio-active count of each particle will depend on the shape of the ~,~
~ ., 1~5~966 particle, the position of the radio-active daughter products in the particle and the orientation of the particle relatively to the radiation detector when the radio-activity of the particle is measured. Because of this problem and the fact that radio-active emission from the particles is not constant many ore particles which are suitable for processing are rejected by the sorter to waste so reducing the efficiency of this type of sorting process.
OBJECT OF THE INVENTION
It is the object of this invention to provide a method of and apparatus for analysing the characteristics of all the particles of a sample of ore from an ore body to determine the sortability of the ore from the body.
UMMARY OE T~IE INVENTION
The invention provides a method of analysing ore particles from a representative sample of ore which method includes the step~q of feeding the particles, spaced fro~n each otller, succe.ssively to a plurality of measuring stations; and at respective ones of the plurality of mea~suring stations, for each particle determ;nin~? at lea~t, ~ mea~surelllent which iq <lependent on the mass of the particle, and D lll(`a.qnrlllellt Wh;C~ q depend~nt on the radioactivity of the partic]e, and recordilll! the mnqs all(l rad;oactivity m~asur(mentR.
Preferably at lenst at one locat;oll the rrldioactivity of (~ch particle ;s measured under condi-~ions wh;cll ~pproximDte conditions prevail;ng in a working ore sorter.
Opt;onally, depending on the analysis required, at least at one location a measure is made of at least one of a spectral component, reflectivity. X-ray fluorescence, conductiv;ty or magnetic susceptibility, of each particle.
6~
In addition the method may include the step, during the movement of each particle to one of the locations, of measuring the physical dimensions of the particle.
The measurements may be recorded by means of a computer and once the characteristic measurements of each particle have been assimilated by the com-puter the characteristic of the particles are presented in a printout or other suitable form to enable characteristic tabulations or graphs to be prepared.
The graphs are drawn in a form appropriate for the purpose of the analysis, i.e. to determine the ore sortabi]ity, the sorting efficiency of a sorter, misplacecl particles in a sort, etc.
The invention also provides apparatus for analysing ore particles from a representative sample of the ore which apparatus comprises conveyor means for moving a plurality of the particles, spacec! from each other, ial succession to a plurality of measuring stations, means at a first measuring station for obtaining a measurement of the mass of each particle, means at a second measuring station for obt;l-ining a measurelllent of the radio.lctivity ot each particle, and means for recorcling tlle m;lss alld rilclio;lctivity me.lsuremerlts.
In adclitioll the ullpar;ltus inclucles me;llls at one location ~for measur-ing the radioactivity ol cucll p;lrticle nllder conclitiolls whicll al)prox:imate conditions prev;lilillg in a worlcillg ore sorter.
TllC ;l~ a:l`;ltlls IlI.ly .llS(l illCIlldC IllC;IllS ;It OllC loc;ltiol~ for mCaSIJring at least OllC`, of the rel`lectivity, X--ray fluorescence, condllctivity, magnetic susceptibility, or a spectral coml)onent, ol each particle.
Use may be made of a computer programmed to assimilate the measured characteristics oF each particle. 'rhe computer may be connected to each measuring station or location of the apparatus.
-4_ ~5~966 The conveyor means of the apparatus may be adapted to deposit the particles sequentially orl beds at selected locations, where the particles are maintained for predetermined time periods.
BRIEF DESCRIPTION OF THE DRAWINGS .
An embodiment of the invention is described by way of example with reference to the drawings in which:
Figure 1 is a partially schematic side elevation of apparatus according to the ;nvention, Figure 2 is a fragmentary perspective view of a station pad of the apparatus of Figure 1, and Figures 3 and 4 depict typical graphs produced by means of the apparatus of Figure 1.
DETAILED DESCRIPTION OF THE DRAWINGS
The analyser apparaius of the invention is shown in the drawings to consist of a frame indicated generally at 10, a conveyor 12, and ore particle receiving and measuring stations 14, 16, 18, 20, 20A, 22 and 24.
The conveyor 12 consists of a substantially rectangular frame 26 which is bridged froln one short end to the other by a plurality of parallel closely spaced and tensioned piano wires 28.
The conveyor is adapted for movement relatively to the frame 10 by means of a first hydraulic or pneumatic jack, not shown, which is connected to act between the frame 10 and a linkage arrangement for lifting the conveyor to the position shown in dotted lines,and a second jack which is adapted to move the raised conveyor to the right from the position shown in dotted lines and~back,again. The length of stroke of the second jack is equal to the distance separating the receiving and measuring stations 14 to 22 of the apparatus.
The stations 14, 18 and 22 each include a particle receiving pad 30 ~56~966 which, as is illustrated in Figure 2, includes a plurality of grooves in which the wires 28 of the eonveyor are located clear of both the upper surfaee of the pad and the bases of the grooves when the frame 26 is in the position illustrated in solid lines in the drawing. The pads at the stations l~ and 22 are fixed to the frame 10 and the pad at the station 18 is loeated on a load cell transducer 32 which is fixed to the frame 10.
The measuring station 16 eonsists of an open frame which carries on its inner periphery a plurality of opposed light emitters and sensors whieh establish in use a closely spaced grid of vertical and horizontal light beams.
An arrangement of this kind and the electronies assoeiated therewith for processing the light signals are deseribed in the applieant's Canadian Patent Application Serial No. 372,590 entitled "Volumetric Measurement of Particles"
and filed March 3, 1982. Such an arrangement proves information on the dimen-sions of a particle e.g. its height, projected area, or volume.
The measuring station 20 consists of a housing having walls made Erom radiation free lead. The up and downstream walls o~ the housing are door slabs 36 and 38 which are located for vert;caI movement ;n gnicIes on the housing. Tho uI)per end of the doors are connectecI to a Iifting bridge ~0 which is raisecI.Ind loworocl by means ol a jaek, not shown in the cIrawing.
The lower edges o~ the doors in t1Ieir IowerecI positioIl rest Oll sills which are grooved like the p;lC15 3() to ;ICCOllllt)OCI;ltc thc w;res 2X ol the conveyor. rIIe lowor ~ortions o-f the cIoors are l;ikewise groove(I. SeintiII;Ition sensorsJ not shown, are located ill the housilIg below thc wires 28 in the lowered positior of the conveyor aIld above and spaced Erom the wires in a ~attern to Ineasure raclio-active emission fI~olll a I)article in the housing -from all directions.
The arrangement of the sensors could be similar to that described in the llS~g66 applicant's Canadian Patent Application Serial Nos. 367 157 and 367 J 158 both entitled "Radiometric Methods and Means" and both filed December 19 1980. In the station 20 the particle rests on a pad similar to the pad 30. The sensors located above the conveyor are located i.n a framework which is attached to the doors 36 and 38 so that they are raised and lowered with the doors to permit passage of an ore particle through the housing.
The station 20A is substantially similar in construction and working to the station 20. Ilowever it contains only a single radiation detector of the type employed in a radiometric ore sorter and is intended to provide under laboratory conditions a measure of the count which would be recorded on a working ore sorter by an ore particle.
The measur;ng stati.on 22 includes a fixed particle receiving pad 30 and a spectrum analyser or like instrument 42 which is attached to the lift;ng bridge 40.
The parti.cle discharge station 24 includes an arm 44 which includes a plurality of spaced plates 46 whi.cll in the position shown in tl)e drawing :Eol-m a pad sim:i]ar to the pads 30. Thc .11`111 44 is rotatllble by means ol a jack not shown a.bout a ~:ivot point 50 at which :it is secured to a -I`ixed support.
As tlle arm is ra:i.sed From the illllstr;lted posi.t:ion the pl;ltes 46 pclSS ~:reely between the w:ires 28 iUld in this way a Inlrt.icle call rcadily he ejected f:rom the conveyor l2 A comll~ter 52 is connectc(l to tllc app.lratlls to rccorcl and analyse tlle cl.l.ta gelle:rlltecl ;at eacll ol the st.lt:iOllS 16 18 20 20A and 22.
:[n llse an OI`C` paI`t:i.ClC iS p~ ced on the pad 30 at the station 14.
Tlle conveyor is tllen lifted to the position shown in dottecl lines with the particle resting on the wires 28 of the conveyor. The conveyor is then moved to the right in the drawing and lowered until the particle rests for a pre-:l~S~966 determined time on the pad 30 of the station 18 free of the conveyor wires.
In its passage fronl station 14 to 18 the particle is moved through the light grid at the station 16. The particle, in its passage through the grid, blanks off a number of both the vertical and horizontal light beams of the grid and this information together with the known speed of movement of the particle enables the computer to determine and record the length, breadth and height of the particle and so its volume, all in the manner described in the applicant's Canadian Patent Application Serial No. 372,590 already referred to. At the station 18 the mass of the particle is determined by the transducer 32 and recorded in the computer.
-7a-8 1~S5;~6~
The conveyor 12 is then moved, without lifting, back to the position indicated in solid lines-while-the particle remains resting on the pad 30 at the station 18. A second particle is then placed on the station 14 and the conveyor transport process is repeated. As the second particle is moved to the station 18 the first is moved to the station - - 20. As the conveyor moves the first particle towards the station 20 the lifting bridge 40 raises the doors 36 and 38 until the particle is in the housing. Whèn the frame 26 settles the particle is left on the pad in the housing and the doors are closed to shield the inside of the housing. The pad in the housing is made from a material which does not inhibit the passage of radio-active waves and the sensors surrounding the particle on the pad in the lowered position of the doors 36 and 38 measure, for the period of rest of the particle on the pad, radio-active emission from the particle in all directions. Using this method of radio-active transmission measurement errors due to background e.g.
cosmic radiation and transient emission effects are eliminated. In addition the transmission of the radio-active waves is not significantly attenuated due to shielding of the waves by the bulk of the mass of the particle which may be located between the radio-active daughter products in the particle and one or more sensors located in a fixed plane. Thus the station 20 produces to a considerable degree of accuracy, a measure of the true radioactivity of the particle inside the housing.
The particle radio-active emission is recorded by the cornputer and the cycle of the conveyor is again repeated with a third particle located on the station 14.
On the next cycle the leading particle is moved into the station 20A and a count of the particle's radioactivity is recorded by means of the single detector. The station 20A approximates the physical conditions prevailing on a working model ore sorter but as shielding is provided tne effects of following and preceding particles which manifest themselves under practical conditions are eliminated.
9 1~5~66 The count recorded in this way thus provides a good basis on which to correlate the laboratory derived data to the data produced in the field.
As the first particle is moved from the station 20 the doors 36 and 38 are lifted to permit the second particle to enter the housing and the first to leave it in its passage to the station 20A. On the successive cycle the leading particle is moved to the station 22, in the manner described. Each time the doors of the station 20A are closed, the analyser 42 is lowered to just above the particle at the station 22.
1~ The first particle is thus analysed at the station 22 in respect of its content of one or more specific minerals or elements by means of the spectrum analyser 42.
The spectrum analyser 42 could be replaced, if desired, by suitable instrumentation for measuring the reflectivity, X-ray fluorescence, conductivity, magnetic susceptibility, or other defined characteristic of each particle, or such information could be used in addition to the analyser, being located at an additional measuring station or stations provided for the purpose.
The analyser of the invention is employed principally to determine the characteristics of a representative sample of ore.
It has been established by the applicant that the radioactivity count of an ore particle recorded by a detector in an ore sorting machine is dependent on the true radioactivity content of the particle and at least on one or more of the physical dimensions of the particle, including its height or volume, the mass of the particle and its density. The analyser, in conjunction with the computer, is designed to provide the relevant data in the manner described from representative ore samples so that these relationships can be statistically determined.
:llS~ 6 For example for sorting purposes it is essential to determine, for a given sample, the number c)f particles within defined mass fractions, and the mass of the particles within the defined mass fractions, on a percentage basis.
This information is readily obtained by means of the analyser which provides the mass of each particle at the station 18. It is a simple matter to progratnme the computer to total the masses and to allocate the mass of each particle into one of the defined mass fractions. The computer can output the information in the form of a graph of the type shown in Figure 3 which gives the number of particles, as a percentage, as a function of particle mass fractions. A
similar curve is obtained for the particle mass, again expressed as a per-centage, as a fraction of particle mass.
By sizing the ore sample prior to its analysis the maximum and minimum masses, and the distribution or spread of the particle's masses, can readily be obtained from the computer as a function of the screen sizes.
The volume measuring device at the station 16 provides the shape, dimensions and volume of each particle and the distribution of shapes, and average dimensions of the particles can he ohtained .Incl relate-l to the par-ticle masses, and raclioactivity. Illis informntioll i.s employcd for count compensation purposes in tho nl.lllller descriled in the applicallt's Canadian Patent Application Seri;ll Nos. 366,0()2 alld 33G,()()I, entitle-l "I)isl~ celllent Error Correctioll in Sorting Systellls" .llld Crade l)etermill.ltion" respectively ~ncl both filed l~ecenlber 3, l')~().
rl`he station 20 provi~les an accutate measure o~ the radioactive con-tent of each particle .nlld since this is correlated with the mass of the par-ticLe the computer can readily determine and represent graphically or otherwise the mineral content and the grade, on a percentage basis, of the ore sample as a function of mass. Maximum and average values can be produced.
:~ ', ;, ` .' !
~ c.~ . --10--i~S~966 Once again it should be pointed out that these parameters are critical in the efficient working of a radiometric particle sorter.
~ lOa-" llS~6 Figure 4 illustrates graphically for a representative ore sample the reject and accept fractions expressed as a percentage, as a function of cut off grade, with curve A giving the mineral distribution and curve B the mass distribution. This information is vital in determining the viability of a sorting machine and is produced from the data generated by the analyser of the invention.
In a practical situation the cost of processing a unit mass of ore to recover its mineral content is known. A decision can thus be made on the cut off grade of the ore which should be processed. The sorting machine can then be set to accept or reject at this cut off grade.
If this is at point X, in Figure 4, then curve A gives the percentage of the mineral recovered, and lost, while curve B gives the corresponding mass percentages of the ore body accepted and rejected. Situtations which completely justify the use of a sorter in economic terms occur when the curves A and B are well separated (horizontally) from each other. Ideally, a large percentage of the mineral content should be recovered, with a large percentage of the ore body, in mass terms, being rejected. This implies that a relatively small ore mass has to be processed to recover the bulk of the mineral content.
Finally, it should be pointed out that the analyser of the invention can be used in the described manner to analyse ore particles sampled from the reject or accept fractions of a working ore sorter. The analyser may, if desired, be installed on site, to provide the information more or less in real time.
Since, in the analyser, the various measurements are taken over periods, up to 40 seconds or more, which are long compared to the measurement periods in a working ore sorter, the information obtained from the analyser is accurate and the sorting efficiency of the working sorter can be assessed.
. .
- 12 - .
g66 Inall the analyser measurements.,. to assist in recovering the.particles falling into the different categories e.g. of mass, shape, volume, etc, the arm 44 can be replaced, or followed, by one or more flap gates which are mechanically actuated to sort the particles into the various categories. The categorised particles may then be subjected to additional tests, e.g. by assaying, for verification purposes.
~`
This invention relates to a method of and apparatus for analysing a sample of particulate mineral ore from an ore body.
BACKGROUND TO THE INVENTION
Conventionally, the grade of an ore body is measured by periodically removing a sample of ore from the body, crushing the sample ore and subjecting the crushed sample to chemical analysis to determine its gradé. If the grade of the ore is high enough to warrant the processing of the entire ore body all of the ore and a substantial proportion of waste material, with perhaps the exception of large particles which obviously do not contain the mineral being sought and which are removed by hand from the remainder of the ore, is processed. This method of ore analysis and processing is, in terms of recovery, efficient as a very large percentage of the sought after mineral in the ore is obtained from the ore. However, a major problem with this process is thatvast quantities of unproductive material are processed to arrive at a relatively small volume percentage of the mineral and this is achieved at considerable plant and labour cost.
In deep level gold mining the above problem has been minimised by the use of automatic sorting machines which sort graded particles of a particular size or range of sizes, into particles which have a particular characteristic, such as radio-active emission, which is related to the gold grade of the ore, from particles which do not have the characteristic or have the characteristic helow a predetermined threshold. When the ore has thus been sorted only the accept ore which is the ore having the characteristic above the threshold level is then processed resulting in a considerable saving over the previously described process in both plant utilisation and labour.
In a radiometric sorting process of this type the radiometric measurement of the ore particles is considerably influenced by parameters such as the mass, volume and shape of the particles. For example, the radio-active count of each particle will depend on the shape of the ~,~
~ ., 1~5~966 particle, the position of the radio-active daughter products in the particle and the orientation of the particle relatively to the radiation detector when the radio-activity of the particle is measured. Because of this problem and the fact that radio-active emission from the particles is not constant many ore particles which are suitable for processing are rejected by the sorter to waste so reducing the efficiency of this type of sorting process.
OBJECT OF THE INVENTION
It is the object of this invention to provide a method of and apparatus for analysing the characteristics of all the particles of a sample of ore from an ore body to determine the sortability of the ore from the body.
UMMARY OE T~IE INVENTION
The invention provides a method of analysing ore particles from a representative sample of ore which method includes the step~q of feeding the particles, spaced fro~n each otller, succe.ssively to a plurality of measuring stations; and at respective ones of the plurality of mea~suring stations, for each particle determ;nin~? at lea~t, ~ mea~surelllent which iq <lependent on the mass of the particle, and D lll(`a.qnrlllellt Wh;C~ q depend~nt on the radioactivity of the partic]e, and recordilll! the mnqs all(l rad;oactivity m~asur(mentR.
Preferably at lenst at one locat;oll the rrldioactivity of (~ch particle ;s measured under condi-~ions wh;cll ~pproximDte conditions prevail;ng in a working ore sorter.
Opt;onally, depending on the analysis required, at least at one location a measure is made of at least one of a spectral component, reflectivity. X-ray fluorescence, conductiv;ty or magnetic susceptibility, of each particle.
6~
In addition the method may include the step, during the movement of each particle to one of the locations, of measuring the physical dimensions of the particle.
The measurements may be recorded by means of a computer and once the characteristic measurements of each particle have been assimilated by the com-puter the characteristic of the particles are presented in a printout or other suitable form to enable characteristic tabulations or graphs to be prepared.
The graphs are drawn in a form appropriate for the purpose of the analysis, i.e. to determine the ore sortabi]ity, the sorting efficiency of a sorter, misplacecl particles in a sort, etc.
The invention also provides apparatus for analysing ore particles from a representative sample of the ore which apparatus comprises conveyor means for moving a plurality of the particles, spacec! from each other, ial succession to a plurality of measuring stations, means at a first measuring station for obtaining a measurement of the mass of each particle, means at a second measuring station for obt;l-ining a measurelllent of the radio.lctivity ot each particle, and means for recorcling tlle m;lss alld rilclio;lctivity me.lsuremerlts.
In adclitioll the ullpar;ltus inclucles me;llls at one location ~for measur-ing the radioactivity ol cucll p;lrticle nllder conclitiolls whicll al)prox:imate conditions prev;lilillg in a worlcillg ore sorter.
TllC ;l~ a:l`;ltlls IlI.ly .llS(l illCIlldC IllC;IllS ;It OllC loc;ltiol~ for mCaSIJring at least OllC`, of the rel`lectivity, X--ray fluorescence, condllctivity, magnetic susceptibility, or a spectral coml)onent, ol each particle.
Use may be made of a computer programmed to assimilate the measured characteristics oF each particle. 'rhe computer may be connected to each measuring station or location of the apparatus.
-4_ ~5~966 The conveyor means of the apparatus may be adapted to deposit the particles sequentially orl beds at selected locations, where the particles are maintained for predetermined time periods.
BRIEF DESCRIPTION OF THE DRAWINGS .
An embodiment of the invention is described by way of example with reference to the drawings in which:
Figure 1 is a partially schematic side elevation of apparatus according to the ;nvention, Figure 2 is a fragmentary perspective view of a station pad of the apparatus of Figure 1, and Figures 3 and 4 depict typical graphs produced by means of the apparatus of Figure 1.
DETAILED DESCRIPTION OF THE DRAWINGS
The analyser apparaius of the invention is shown in the drawings to consist of a frame indicated generally at 10, a conveyor 12, and ore particle receiving and measuring stations 14, 16, 18, 20, 20A, 22 and 24.
The conveyor 12 consists of a substantially rectangular frame 26 which is bridged froln one short end to the other by a plurality of parallel closely spaced and tensioned piano wires 28.
The conveyor is adapted for movement relatively to the frame 10 by means of a first hydraulic or pneumatic jack, not shown, which is connected to act between the frame 10 and a linkage arrangement for lifting the conveyor to the position shown in dotted lines,and a second jack which is adapted to move the raised conveyor to the right from the position shown in dotted lines and~back,again. The length of stroke of the second jack is equal to the distance separating the receiving and measuring stations 14 to 22 of the apparatus.
The stations 14, 18 and 22 each include a particle receiving pad 30 ~56~966 which, as is illustrated in Figure 2, includes a plurality of grooves in which the wires 28 of the eonveyor are located clear of both the upper surfaee of the pad and the bases of the grooves when the frame 26 is in the position illustrated in solid lines in the drawing. The pads at the stations l~ and 22 are fixed to the frame 10 and the pad at the station 18 is loeated on a load cell transducer 32 which is fixed to the frame 10.
The measuring station 16 eonsists of an open frame which carries on its inner periphery a plurality of opposed light emitters and sensors whieh establish in use a closely spaced grid of vertical and horizontal light beams.
An arrangement of this kind and the electronies assoeiated therewith for processing the light signals are deseribed in the applieant's Canadian Patent Application Serial No. 372,590 entitled "Volumetric Measurement of Particles"
and filed March 3, 1982. Such an arrangement proves information on the dimen-sions of a particle e.g. its height, projected area, or volume.
The measuring station 20 consists of a housing having walls made Erom radiation free lead. The up and downstream walls o~ the housing are door slabs 36 and 38 which are located for vert;caI movement ;n gnicIes on the housing. Tho uI)per end of the doors are connectecI to a Iifting bridge ~0 which is raisecI.Ind loworocl by means ol a jaek, not shown in the cIrawing.
The lower edges o~ the doors in t1Ieir IowerecI positioIl rest Oll sills which are grooved like the p;lC15 3() to ;ICCOllllt)OCI;ltc thc w;res 2X ol the conveyor. rIIe lowor ~ortions o-f the cIoors are l;ikewise groove(I. SeintiII;Ition sensorsJ not shown, are located ill the housilIg below thc wires 28 in the lowered positior of the conveyor aIld above and spaced Erom the wires in a ~attern to Ineasure raclio-active emission fI~olll a I)article in the housing -from all directions.
The arrangement of the sensors could be similar to that described in the llS~g66 applicant's Canadian Patent Application Serial Nos. 367 157 and 367 J 158 both entitled "Radiometric Methods and Means" and both filed December 19 1980. In the station 20 the particle rests on a pad similar to the pad 30. The sensors located above the conveyor are located i.n a framework which is attached to the doors 36 and 38 so that they are raised and lowered with the doors to permit passage of an ore particle through the housing.
The station 20A is substantially similar in construction and working to the station 20. Ilowever it contains only a single radiation detector of the type employed in a radiometric ore sorter and is intended to provide under laboratory conditions a measure of the count which would be recorded on a working ore sorter by an ore particle.
The measur;ng stati.on 22 includes a fixed particle receiving pad 30 and a spectrum analyser or like instrument 42 which is attached to the lift;ng bridge 40.
The parti.cle discharge station 24 includes an arm 44 which includes a plurality of spaced plates 46 whi.cll in the position shown in tl)e drawing :Eol-m a pad sim:i]ar to the pads 30. Thc .11`111 44 is rotatllble by means ol a jack not shown a.bout a ~:ivot point 50 at which :it is secured to a -I`ixed support.
As tlle arm is ra:i.sed From the illllstr;lted posi.t:ion the pl;ltes 46 pclSS ~:reely between the w:ires 28 iUld in this way a Inlrt.icle call rcadily he ejected f:rom the conveyor l2 A comll~ter 52 is connectc(l to tllc app.lratlls to rccorcl and analyse tlle cl.l.ta gelle:rlltecl ;at eacll ol the st.lt:iOllS 16 18 20 20A and 22.
:[n llse an OI`C` paI`t:i.ClC iS p~ ced on the pad 30 at the station 14.
Tlle conveyor is tllen lifted to the position shown in dottecl lines with the particle resting on the wires 28 of the conveyor. The conveyor is then moved to the right in the drawing and lowered until the particle rests for a pre-:l~S~966 determined time on the pad 30 of the station 18 free of the conveyor wires.
In its passage fronl station 14 to 18 the particle is moved through the light grid at the station 16. The particle, in its passage through the grid, blanks off a number of both the vertical and horizontal light beams of the grid and this information together with the known speed of movement of the particle enables the computer to determine and record the length, breadth and height of the particle and so its volume, all in the manner described in the applicant's Canadian Patent Application Serial No. 372,590 already referred to. At the station 18 the mass of the particle is determined by the transducer 32 and recorded in the computer.
-7a-8 1~S5;~6~
The conveyor 12 is then moved, without lifting, back to the position indicated in solid lines-while-the particle remains resting on the pad 30 at the station 18. A second particle is then placed on the station 14 and the conveyor transport process is repeated. As the second particle is moved to the station 18 the first is moved to the station - - 20. As the conveyor moves the first particle towards the station 20 the lifting bridge 40 raises the doors 36 and 38 until the particle is in the housing. Whèn the frame 26 settles the particle is left on the pad in the housing and the doors are closed to shield the inside of the housing. The pad in the housing is made from a material which does not inhibit the passage of radio-active waves and the sensors surrounding the particle on the pad in the lowered position of the doors 36 and 38 measure, for the period of rest of the particle on the pad, radio-active emission from the particle in all directions. Using this method of radio-active transmission measurement errors due to background e.g.
cosmic radiation and transient emission effects are eliminated. In addition the transmission of the radio-active waves is not significantly attenuated due to shielding of the waves by the bulk of the mass of the particle which may be located between the radio-active daughter products in the particle and one or more sensors located in a fixed plane. Thus the station 20 produces to a considerable degree of accuracy, a measure of the true radioactivity of the particle inside the housing.
The particle radio-active emission is recorded by the cornputer and the cycle of the conveyor is again repeated with a third particle located on the station 14.
On the next cycle the leading particle is moved into the station 20A and a count of the particle's radioactivity is recorded by means of the single detector. The station 20A approximates the physical conditions prevailing on a working model ore sorter but as shielding is provided tne effects of following and preceding particles which manifest themselves under practical conditions are eliminated.
9 1~5~66 The count recorded in this way thus provides a good basis on which to correlate the laboratory derived data to the data produced in the field.
As the first particle is moved from the station 20 the doors 36 and 38 are lifted to permit the second particle to enter the housing and the first to leave it in its passage to the station 20A. On the successive cycle the leading particle is moved to the station 22, in the manner described. Each time the doors of the station 20A are closed, the analyser 42 is lowered to just above the particle at the station 22.
1~ The first particle is thus analysed at the station 22 in respect of its content of one or more specific minerals or elements by means of the spectrum analyser 42.
The spectrum analyser 42 could be replaced, if desired, by suitable instrumentation for measuring the reflectivity, X-ray fluorescence, conductivity, magnetic susceptibility, or other defined characteristic of each particle, or such information could be used in addition to the analyser, being located at an additional measuring station or stations provided for the purpose.
The analyser of the invention is employed principally to determine the characteristics of a representative sample of ore.
It has been established by the applicant that the radioactivity count of an ore particle recorded by a detector in an ore sorting machine is dependent on the true radioactivity content of the particle and at least on one or more of the physical dimensions of the particle, including its height or volume, the mass of the particle and its density. The analyser, in conjunction with the computer, is designed to provide the relevant data in the manner described from representative ore samples so that these relationships can be statistically determined.
:llS~ 6 For example for sorting purposes it is essential to determine, for a given sample, the number c)f particles within defined mass fractions, and the mass of the particles within the defined mass fractions, on a percentage basis.
This information is readily obtained by means of the analyser which provides the mass of each particle at the station 18. It is a simple matter to progratnme the computer to total the masses and to allocate the mass of each particle into one of the defined mass fractions. The computer can output the information in the form of a graph of the type shown in Figure 3 which gives the number of particles, as a percentage, as a function of particle mass fractions. A
similar curve is obtained for the particle mass, again expressed as a per-centage, as a fraction of particle mass.
By sizing the ore sample prior to its analysis the maximum and minimum masses, and the distribution or spread of the particle's masses, can readily be obtained from the computer as a function of the screen sizes.
The volume measuring device at the station 16 provides the shape, dimensions and volume of each particle and the distribution of shapes, and average dimensions of the particles can he ohtained .Incl relate-l to the par-ticle masses, and raclioactivity. Illis informntioll i.s employcd for count compensation purposes in tho nl.lllller descriled in the applicallt's Canadian Patent Application Seri;ll Nos. 366,0()2 alld 33G,()()I, entitle-l "I)isl~ celllent Error Correctioll in Sorting Systellls" .llld Crade l)etermill.ltion" respectively ~ncl both filed l~ecenlber 3, l')~().
rl`he station 20 provi~les an accutate measure o~ the radioactive con-tent of each particle .nlld since this is correlated with the mass of the par-ticLe the computer can readily determine and represent graphically or otherwise the mineral content and the grade, on a percentage basis, of the ore sample as a function of mass. Maximum and average values can be produced.
:~ ', ;, ` .' !
~ c.~ . --10--i~S~966 Once again it should be pointed out that these parameters are critical in the efficient working of a radiometric particle sorter.
~ lOa-" llS~6 Figure 4 illustrates graphically for a representative ore sample the reject and accept fractions expressed as a percentage, as a function of cut off grade, with curve A giving the mineral distribution and curve B the mass distribution. This information is vital in determining the viability of a sorting machine and is produced from the data generated by the analyser of the invention.
In a practical situation the cost of processing a unit mass of ore to recover its mineral content is known. A decision can thus be made on the cut off grade of the ore which should be processed. The sorting machine can then be set to accept or reject at this cut off grade.
If this is at point X, in Figure 4, then curve A gives the percentage of the mineral recovered, and lost, while curve B gives the corresponding mass percentages of the ore body accepted and rejected. Situtations which completely justify the use of a sorter in economic terms occur when the curves A and B are well separated (horizontally) from each other. Ideally, a large percentage of the mineral content should be recovered, with a large percentage of the ore body, in mass terms, being rejected. This implies that a relatively small ore mass has to be processed to recover the bulk of the mineral content.
Finally, it should be pointed out that the analyser of the invention can be used in the described manner to analyse ore particles sampled from the reject or accept fractions of a working ore sorter. The analyser may, if desired, be installed on site, to provide the information more or less in real time.
Since, in the analyser, the various measurements are taken over periods, up to 40 seconds or more, which are long compared to the measurement periods in a working ore sorter, the information obtained from the analyser is accurate and the sorting efficiency of the working sorter can be assessed.
. .
- 12 - .
g66 Inall the analyser measurements.,. to assist in recovering the.particles falling into the different categories e.g. of mass, shape, volume, etc, the arm 44 can be replaced, or followed, by one or more flap gates which are mechanically actuated to sort the particles into the various categories. The categorised particles may then be subjected to additional tests, e.g. by assaying, for verification purposes.
~`
Claims (8)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of analysing ore particles from a representative sample of ore which method includes the steps of feeding the particles, spaced from each other, successively to a plurality of measuring stations; and at respective ones of the plurality of measuring stations, for each particle, determining, at least, a measurement which is dependent on the mass of the particle, and a measurement which is dependent on the radioactivity of the particle, and recording the mass and radioactivity measurements.
2. A method according to claim 1 which includes the steps of determining and recording the number of particles within defined mass fractions, and the mass of the particles within each of the defined mass fractions, as proportions respectively of the number of particles in the ore sample, and the mass of the ore sample.
3. A method according to claim 1 which indicates the steps of determining, for each particle, at a further measuring station, a measurement of the volume of the particle, and recording the volume measurement.
4. A method according to claim 1 including the further step of determining the grade of the ore sample as a function of particle mass.
5. A method according to claim 4 including the step of sorting the particles into predetermined categories for verification purposes.
6. Apparatus for analysing ore particles from a representative sample of the ore which apparatus comprises conveyor means for moving a plurality of the particles, spaced from each other, in succession to a plurality of measuring stations, means at a first measuring station for obtaining a measurement of the mass of each particle, means at a second measuring station for obtaining a measurement of the radioactivity of each particle, and means for recording the mass and radioactivity measurements.
7. Apparatus according to claim 6 which includes means at a third measuring station for obtaining a measurement of the physical dimensions of each particle.
8. Apparatus according to claim 7 which includes means for sorting the particles into predetermined categories.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA796728 | 1979-12-12 | ||
| ZA79/6728 | 1979-12-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1150966A true CA1150966A (en) | 1983-08-02 |
Family
ID=25574417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000366560A Expired CA1150966A (en) | 1979-12-12 | 1980-12-11 | Mineral ore analyser |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS56100338A (en) |
| AU (1) | AU542927B2 (en) |
| CA (1) | CA1150966A (en) |
| DE (1) | DE3046807C2 (en) |
| FR (1) | FR2472188B1 (en) |
| GB (1) | GB2066456B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4854163A (en) * | 1987-09-28 | 1989-08-08 | Amoco Corporation | Beltless core conveyor system for wellsite analysis |
| DE3914864C2 (en) * | 1989-05-05 | 1998-10-08 | Nis Ingenieurgesellschaft Mbh | Method and device for measuring radioactive components |
| AUPN226295A0 (en) * | 1995-04-07 | 1995-05-04 | Technological Resources Pty Limited | A method and an apparatus for analysing a material |
| DE19716672C1 (en) * | 1997-04-21 | 1998-06-10 | Robert Bscheider | Procedure for quantitive recording of packed stale products returned from food factories |
| US6448564B1 (en) | 2000-05-30 | 2002-09-10 | Gtsd Sub Iii | Apparatus, methods, and systems for assaying materials |
| DE102007051135A1 (en) * | 2007-10-24 | 2009-04-30 | Katz, Elisabeth | Apparatus for the online determination of the content of a substance and method using such a device |
| JP6379756B2 (en) * | 2014-07-07 | 2018-08-29 | 住友金属鉱山株式会社 | Data processing apparatus, data processing program, data processing method, and processing condition determination method |
| US9669433B2 (en) * | 2014-11-19 | 2017-06-06 | JL Robotics Inc. | Universal mineral separator |
| GB2551980A (en) * | 2016-06-30 | 2018-01-10 | Commw Scient Ind Res Org | Method and system for low level metal analysis of mineral samples |
| DE102022125632A1 (en) | 2022-10-05 | 2024-04-11 | GS Gesellschaft für Umwelt- und Energie-Serviceleistungen mbH | Process for treating bulk material consisting predominantly of metallic objects and device for carrying out such a process |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE958102C (en) * | 1955-04-02 | 1957-02-14 | Hans Heidenreich | Method and device for the mechanical extraction of coal, ores and other minerals |
| FR1240196A (en) * | 1959-10-13 | 1960-09-02 | Method and device for sorting radioactive ores | |
| AU475297B2 (en) * | 1972-06-09 | 1976-08-19 | Commonwealth Scientific And Industrial Research Organisation | Analysis utilizing neutron irradiation |
| JPS5214118B2 (en) * | 1972-12-19 | 1977-04-19 | ||
| JPS5057489A (en) * | 1973-09-20 | 1975-05-19 | ||
| JPS5090389A (en) * | 1973-12-11 | 1975-07-19 | ||
| US3999068A (en) * | 1975-06-16 | 1976-12-21 | Union Carbide Corporation | Apparatus for measuring the radioactivity of the contents of tube like receptacles |
| JPS5924383B2 (en) * | 1977-09-02 | 1984-06-08 | 住友金属工業株式会社 | Continuous automatic quality measurement method and device for sintered ore |
-
1980
- 1980-12-04 AU AU65066/80A patent/AU542927B2/en not_active Ceased
- 1980-12-10 GB GB8039632A patent/GB2066456B/en not_active Expired
- 1980-12-11 CA CA000366560A patent/CA1150966A/en not_active Expired
- 1980-12-11 FR FR8026346A patent/FR2472188B1/en not_active Expired
- 1980-12-12 JP JP17571080A patent/JPS56100338A/en active Pending
- 1980-12-12 DE DE3046807A patent/DE3046807C2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3046807A1 (en) | 1981-09-03 |
| AU542927B2 (en) | 1985-03-28 |
| GB2066456A (en) | 1981-07-08 |
| FR2472188B1 (en) | 1985-09-06 |
| GB2066456B (en) | 1983-07-20 |
| DE3046807C2 (en) | 1984-08-23 |
| JPS56100338A (en) | 1981-08-12 |
| FR2472188A1 (en) | 1981-06-26 |
| AU6506680A (en) | 1981-06-18 |
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