CA1230404A - Method for geophysical exploration of polymineral ore bodies - Google Patents
Method for geophysical exploration of polymineral ore bodiesInfo
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- CA1230404A CA1230404A CA000462982A CA462982A CA1230404A CA 1230404 A CA1230404 A CA 1230404A CA 000462982 A CA000462982 A CA 000462982A CA 462982 A CA462982 A CA 462982A CA 1230404 A CA1230404 A CA 1230404A
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Abstract
METHOD FOR GEOPHYSICAL EXPLORATION OF POLYMINERAL ORE
BODIES
Abstract A method for geophysical exploration of polymineral ore bodies, wherein elastic waves are excited in a rock mass under study to induce an electrostatic polarization in ore bodies, with subsequent excitation of the elastic waves during the time interval within which the electrostatic pola-rization charge still exists, and recording an electromagne-tic pulse radiation generated by the ore bodies under the action of the elastic waves, the number of pulse packets of the radiation determining the number of said ore bodies.
BODIES
Abstract A method for geophysical exploration of polymineral ore bodies, wherein elastic waves are excited in a rock mass under study to induce an electrostatic polarization in ore bodies, with subsequent excitation of the elastic waves during the time interval within which the electrostatic pola-rization charge still exists, and recording an electromagne-tic pulse radiation generated by the ore bodies under the action of the elastic waves, the number of pulse packets of the radiation determining the number of said ore bodies.
Description
OD FOR OEOPHYSICA~ E~PLOR~TIOlJ O~ POL~ RAL
i~RE i3 The invention relates -to the geophysics and it deal~
wi-th methods ~or discovering mineral deposit~, involving seismic exploration and explora-tion usin~ electro~agnetic oscillations, and mo~e spec~ ically it deals with a method ~or geoph~sical exploration o~ polymineral ore bodies.
A method for geophysical exploration Q~ pol~minsral o~e bodies is used at the stage o~ prospecting and explora-tion o~ ore bodies con-taining tin, gold, lead, zinc, merclry;
molybdenum, tungsten9 antimony, rare-earth metals and it is especially e~fective in explorin~r ore bodies at the stage o~ working o~ ~nown depositsO
~ istribu-tion of polymineral ore bodies in space in the county rock is rather complicated. Thickness o~ ore bodies which are worthy of commercial working depends on the vallle o~ a mi~eral, a~d in certain application~ it may be e~pedient to work ore bodies several tens ~ n-timeter thick.
'~he eæplora-tion o~ polymineral ore bodies is generally conducted by using geological methods comprising driving explora~ion working~S drilli~g a system o~ exploration bore-holes and, a~ter studying the composition o~ cores, deter-minin~ the presence o~ an ore body. The boreholes are general-ly spaced apart at about 20 m. This method is rather labour--consuming and requires much time a~d money, yet it is not adequately ef~ec-tive~
i~RE i3 The invention relates -to the geophysics and it deal~
wi-th methods ~or discovering mineral deposit~, involving seismic exploration and explora-tion usin~ electro~agnetic oscillations, and mo~e spec~ ically it deals with a method ~or geoph~sical exploration o~ polymineral ore bodies.
A method for geophysical exploration Q~ pol~minsral o~e bodies is used at the stage o~ prospecting and explora-tion o~ ore bodies con-taining tin, gold, lead, zinc, merclry;
molybdenum, tungsten9 antimony, rare-earth metals and it is especially e~fective in explorin~r ore bodies at the stage o~ working o~ ~nown depositsO
~ istribu-tion of polymineral ore bodies in space in the county rock is rather complicated. Thickness o~ ore bodies which are worthy of commercial working depends on the vallle o~ a mi~eral, a~d in certain application~ it may be e~pedient to work ore bodies several tens ~ n-timeter thick.
'~he eæplora-tion o~ polymineral ore bodies is generally conducted by using geological methods comprising driving explora~ion working~S drilli~g a system o~ exploration bore-holes and, a~ter studying the composition o~ cores, deter-minin~ the presence o~ an ore body. The boreholes are general-ly spaced apart at about 20 m. This method is rather labour--consuming and requires much time a~d money, yet it is not adequately ef~ec-tive~
-2 ~30~
There are also geophysical methods ~or explor3tion of polymineral ore bodies -~hich ma1~e it pos_ible ~o ac-celerate the ~rospecting opera-tio~ at lower cost. Poly-mineral ore bodies ~re known to be prone to an electros--ta~ic polarizatio-n under -the action of an external elec-tric field, and this is -the basi~ o~ a me-thod lor e~ploration of polymîneral ore bodies by the in~uced polarization technique (c~. V.A. ~omarov, Electrical Exploration by the Induced Polarization Technique, 198~, Leningrad, Nedra Publishing House, p. 391). ~he me~hods comprises causing alternatin~ or direct current to flow -through a mass o~ rocks enclosin~ ore bodies under study and measurin~
the tra-nsition characteristic of the induced polarization of the medium, the presence o~ ore bodies in the polariza-tion zone bein~ assessed by anomalies in this characteristic.
~ his me-thod canno-t, however, be used to determine -the number o~ contiguous ore bodies bg the revealed anomaly.
In addition9 under the condi~ions o~ a deposit bein~ wo~ked t especially in case there are hi~hl~ conduc-tive country rocks, it is necessarJ -to have a strong curren-t (o~ the order o~ hundreds Amperes) which is practically impossible. The use of such method in mines i9 limited by the presence of elo~gated conductive objects such as pipelines, rails and cable 9 .
Enown in the art is a method ~or geophysical explora-tion o~ polymineral ore bodies (c~ USSR Inventor's Cer-ti~icate No. 972453, filed March 43 1981, publ. Nov. 7,
There are also geophysical methods ~or explor3tion of polymineral ore bodies -~hich ma1~e it pos_ible ~o ac-celerate the ~rospecting opera-tio~ at lower cost. Poly-mineral ore bodies ~re known to be prone to an electros--ta~ic polarizatio-n under -the action of an external elec-tric field, and this is -the basi~ o~ a me-thod lor e~ploration of polymîneral ore bodies by the in~uced polarization technique (c~. V.A. ~omarov, Electrical Exploration by the Induced Polarization Technique, 198~, Leningrad, Nedra Publishing House, p. 391). ~he me~hods comprises causing alternatin~ or direct current to flow -through a mass o~ rocks enclosin~ ore bodies under study and measurin~
the tra-nsition characteristic of the induced polarization of the medium, the presence o~ ore bodies in the polariza-tion zone bein~ assessed by anomalies in this characteristic.
~ his me-thod canno-t, however, be used to determine -the number o~ contiguous ore bodies bg the revealed anomaly.
In addition9 under the condi~ions o~ a deposit bein~ wo~ked t especially in case there are hi~hl~ conduc-tive country rocks, it is necessarJ -to have a strong curren-t (o~ the order o~ hundreds Amperes) which is practically impossible. The use of such method in mines i9 limited by the presence of elo~gated conductive objects such as pipelines, rails and cable 9 .
Enown in the art is a method ~or geophysical explora-tion o~ polymineral ore bodies (c~ USSR Inventor's Cer-ti~icate No. 972453, filed March 43 1981, publ. Nov. 7,
3--~:3~
1982, Of~, Bull. No. 41, Cl~ G 01 V 11/00) ,7hich ~a~es it possible to ~etermine the number of ore oodies in a mass o~ county rocks under study in a more accura~e mannsr, ~he method comprises exciting elastic waves in t~e mass of rocks enclosing ore bodies and recording an electroma,--ne-tic pulse radiation genexated by the ore bodies under the action o~ -these elastic waves, the number o~ pol~mi-neral ore bodies in the roc~ mass under study 'oeing deter-mined by the number o~ pulse packe~s.
~ he accurac~ o~ determination o~ the number o~ pol~-mineral ore bodies in ~he rock mass under study by t is method is rather inadequate since it is not possible bO
define ore bodies of a small thickness as ~he intensi-t~
of electroma~netic radiation depends on the ore bod~
thickness. In addi-tion, the i~tensity of an electroma~netic pulse radia-tion ~enerated by the ore body also depends on mineral composi-tion and structure of the ore body~
It is an object of ~he invention to iulprove the ac-curacy o~ determination o~ the number o~ ore bodies occurring in a rock mass bein~ studied, Thi~ object is accomplished by that in a method ~or geophysical exploration o~ pol~mineral ore bodies compri-5ing excitin~ elastic waves in the roc~ enclosing ore bodies ~and recordi~g an elec~romagnetic pulse radia-tio~ ge-nerated by the ore bodies under the ac-tion o~ ~he elastic waves, the number o~ polymineral ore bodies being determined b~-the number o~ pulse packets of the radia~ion, acoording ~23~
to the invention, the elastic waves inducing a~ el~o~ro~-tatic polarization are first excited in ths ~ass ol ~ocks with a second excitation of ~he elastic ~.~aves bein~ eTfecve.
durin~ -the -time interval within which the electrosta',ic polarization charge ,-tlll e~ists, In case a known ore bodJ is availa~le in the rnass of rocks, it is advisable also to record variation o~ -the e~ectros-tatic polarization charOe of such an ore body, the subsequent excita-tion of the elastic waves being eI'-fected when ~the charge is at its maximumO
It is kno~Jn ~hat an elec~romag~etic pulse ra~iation appears in polymineral ore bodies under -the action o~ an elas-tic wave. The in-tensity o~ the electric ~ield at a distance of 1 m ~rom -the source o~ the elastic wave is reater than 107-1~8 ~/m and is higher than the in-tensit~
o~ piezoelectric, contact and seismoelectric field by a ~actor of hundreds and even thousands.
~ he charge rise time of the electrostatic polariza-tion and the relaxation time depend on mlneral composition o~
an ore body, The charge rlse -time ranges frcm several seconds to tens o~ seconds. ~he charge relaxation ~ime is s~veral mlnutes~
~ 11 polymineral bodies in a rock mass being studied a-re polarized whatever their thickness.
The amplitude of the electroma,~netic radiation pulses ge~erated u~der -the action o~ the elas-tic waves ~rom the polarized ore bodies is grea-ter than -the a~plitude o~
pulses o~ the electromagneti~ xadia-tion ge~era-ted by no~-polarized ore ~odies. At the moment at ~lhich the Glestro-sta~ic olariza-tion char~e o~ an ore body reaches its maximum value -the a,nplitude o~ the electromagnetic radia-tion induced by -the elastic l~aves excited in ~he rock mass at this momen-t increases b~ from 2 to 5 times deriendi~g on mineral composition of the ore body. ~his allo~s ~he electromagnetic radia~ion ~rom small-thickness ~re bodies and lrom ore bodies located at a substantial distance ~rom the point of recording o~ the electromagnetic radia~io~
to be recorded thus improving the accuracy o~ determi~ation o-f the ~umber o~ ore bodies in the rock mass being studied.
~ he invention will now be described ~ith re~erence to a speci~ic embodimen-t o~ a me-thod lor geophysical e~plora-tion of pol-Jmineral ore bodies illustrated in the accompan~ing drawin~s, in which:
Fi,ure 1 is a time char-t showi~g varia-tio~ ol -the electros-tatic polarization charge of ore bodies having the Oalenite-sphalerite composition, according to the invention;
~ igure 2 i9 a time chart showing variation o~ the electrostatic polarization charge of ore bodies o~ the ~uar-tz-an-timonite~ci~nabar composition;
Figure ~ i5 a time chart ~howing the electxomagne-tic pulse radia-tion.
A method fox geophysical exploration of polymineral ore bodies con.sists in the followi~g.
Elastic waves are exci-ted in a rock mass under study to induce an electromagnetic radiation and an elsct~os~ic polarization of ore bodies. For that ?urpose, an e~plo~ e charge is blown-up, the charge yield dependin~ on ~he -~olw~e o~ the rock mass bei~g s-tudied.
Exploration by -the method according ~o -the invention is mos-t ~requently conduc-ted in a mass o~ rocks rangin~ up to about 10~ m ~rom the p~in-t o~ explosionO ~he charge ~ield mainly depends on the conditions for the propagation ol ths elastic waves -through the mass o~ rocks under stud~, the mass size and mineral composition of ore bodies.
Generally the mass o~ a char~e~ e.g. o~ ammonite ohar~e does not exceed 6 ~g~ In applications vlhere the mass under s-tudy is small- irom 10 to 20 m, the elastic-waves can be excited by using non-explosive sources. An explosive cbarge is generally placed in the mou-th o~ an available borehole or in a recess at -the ~loor o~ a working.
The electros-tatic ~ield o~ polymineral ore bodies ma-ni~ests itsel~ in the ~orm of a posi-tive charge a-t their sur~ace~ and the time charts 1 (Figure 1) and 2 (~iæure 2) showing Yaria~ions o~ the charge ~or two deposits that have been investigated are given in the drawings, wherein the surface charge densit~ ~ in 10~9c~m2 is plotted on the ordinates a~d time in seconds is plotted on the abscissae.
By -the -time mome~t to~0 (be~ore the momen~ of explosion) there is a natural ch~rg~ o~ ore bodies with a sur~ace ~ensit~ ~ O (~ig. 1) and ~ O (Fi~ure 2). A~ter the explosio~ a charge rise occurs5 ~he time $max in which the charge attains its maxi~um value ~ max depending on mineral composition o~ an ore body and is about tma~=1 s for the galenite-sphalerite ore bodies (Figure 1) and about t~g=14 s for the quar~tæ-antimonite-cinnabar ore bodie~. The charge relaxation time is up to several minutes.
~ hen, during the time :Lnterval within which the electrostatic polarization of ore bodies still obtains, elastic waves are re-excited in the rock mass under s~ud7, e.O~. b~ blowing-up an explosive charge~ The seco,nd explosion i9 generally made adaacent -to -the point o~ the ~irst explo-sion~ at a distance precluding detonation o~ the explosive.
~he weiOh~ o~ the second explosive charge may be lo~er than that o~ the firs~ onec The second explosion can, e.g.
be made with an ammonite charge of 1 kgo The optimum time for the re-excitation o~ the elastic waves i9 the mome~t at which the value of the el~ctrostatic polarization charge achieves its maximum. In order to de-termine this time momen-t, an instrument for recording ~Jariation o~ -the electrostatic polarization charge, e.g.
an electro~eter with preriodical screeni~g o~ the measuring electrode i9 ins-talled in a known ore body undercut by a worki~g. By watchi~g 0~ the sereen of an electronic oscillo-soope or a like instrument varia~ion o~ the electrostatic polarizatio~ pote~tial, the maxi~um value of charge is visually determin~d and the re-e~citation o~ the elastic waves and recording o~ the electromagnetic pulse radiatio~
~3~
of -the ore bodies are e~ected at that moment, the nlmber o~ packe-ts o~ the radia-tion pulses determini~g the num'oer of polymineral ore bodies.
Figure 3 shows a time chart illustrati~, the diagram o~ the electroma~netic ~ulse radiation. The vol-tags U
in Volts at the output of' a recorder is plotted on the ordinates and time t in ms is plotted on the abscissae7 ~he ore body radia-tion is in the ~orm ol packets 3,4,5 o~
noise-like signals consisting o~ short pulses of different amplitude and polarity. ~hree packets 3, 4, 5 oY ~ulses can be seen on -the dia~ram ~rom which it follo~Js that in -the rock mass under study -three ore bodies worthy of co~mer-cial worki~g are discovered by t'ne method according to the invention.
For better understandinO o~ the in~-ention; the ~ol-lowing speci~ic example o~ its prac-tical realization is given belowq ~ he method ~or geophJsical exploration o~ polymineral ore bodies was tested on a deposit for prospecting ore bodies o~ the quar~tz-atimonite-cinnabar composi-tion. An electrometer ~or recording variation o~ the electrostatic polariza~ion charge o~ -the ore bod~ was installed on an ore body stripped by driving a worki~g. ~hen an ammonite charge o~ 4 kg was blown-up a-t one point o~ the working.
Under the aotion of an elastic wave caused by the explosion an electromagnetic radiation was genera-ted by ore bodies available in the rock mass under stud~, and _9_ variation o~ the electrostatic polarizatio~ charOe was recorded and visuall~ observed. At the mo~ent wnen ~he density of the electrostatic polarization charOe achis-Jed the maximum value of 6 _~.10 ~C/m2, a second explosion of an ammoni-te charOe o~ as made 14 s after the lrs.
explosion a-t a distance of about 1~ m from the poi~t of e~citation of the elastic waves by the ~irst charge. The ampli~ude of the electromagnetlc radiation pulses was 0.5; 1.3; 2.0 and 0.8 V ~or various objec-ts. ~herefore, four ore bodies were recorded in-the rock mass under study.
To determi~e the distance to a respec-tive ore body, t~ pulse arri~al time was also recorded. ~his -time was for -the above amplitudes ~.25; o.1; 1~.15; 14.1 ms, res-pec~ivel~.
Given the velocity of propaga-tion o~ the elastic wave through the county rock enclosing the ore body 7 -this distance could be easil~ found ~hus, with a velocity in solid limestones of 5.5 m/ms, ~he dis-tance -to the most remo-te ore body is 14 1 ms05.5 m/ms=78 m from the point of explosion In -the process of verification, these ~our ore bodies were actually undarcu-t by exploration boreholes.
For comparing the me~hod according ~o the inven-tion with the prior art method, the amplitude o~ pulses o~ -the elec-tromagne-tic radiation of ore bodies induced by the firs-t explosion was recorded. Three ore bodies were dis-coveredO ~he amplitudes o~ pulses were 0~1, 004; and 1 0 V, respectively, with their arrival -times 3~2; 6.1 and 1~.2 ms, respectively~ There~ore, the amplitude o~ the si~n31s emitted by the polarized oodies increased bJ a fac-tor ~ro~ 2 -to 5 so that an ore body could be discoverea tha-t had not been discovered after the ~irst explosion ~hen the ore bodies had no-t been polarized.
1982, Of~, Bull. No. 41, Cl~ G 01 V 11/00) ,7hich ~a~es it possible to ~etermine the number of ore oodies in a mass o~ county rocks under study in a more accura~e mannsr, ~he method comprises exciting elastic waves in t~e mass of rocks enclosing ore bodies and recording an electroma,--ne-tic pulse radiation genexated by the ore bodies under the action o~ -these elastic waves, the number o~ pol~mi-neral ore bodies in the roc~ mass under study 'oeing deter-mined by the number o~ pulse packe~s.
~ he accurac~ o~ determination o~ the number o~ pol~-mineral ore bodies in ~he rock mass under study by t is method is rather inadequate since it is not possible bO
define ore bodies of a small thickness as ~he intensi-t~
of electroma~netic radiation depends on the ore bod~
thickness. In addi-tion, the i~tensity of an electroma~netic pulse radia-tion ~enerated by the ore body also depends on mineral composi-tion and structure of the ore body~
It is an object of ~he invention to iulprove the ac-curacy o~ determination o~ the number o~ ore bodies occurring in a rock mass bein~ studied, Thi~ object is accomplished by that in a method ~or geophysical exploration o~ pol~mineral ore bodies compri-5ing excitin~ elastic waves in the roc~ enclosing ore bodies ~and recordi~g an elec~romagnetic pulse radia-tio~ ge-nerated by the ore bodies under the ac-tion o~ ~he elastic waves, the number o~ polymineral ore bodies being determined b~-the number o~ pulse packets of the radia~ion, acoording ~23~
to the invention, the elastic waves inducing a~ el~o~ro~-tatic polarization are first excited in ths ~ass ol ~ocks with a second excitation of ~he elastic ~.~aves bein~ eTfecve.
durin~ -the -time interval within which the electrosta',ic polarization charge ,-tlll e~ists, In case a known ore bodJ is availa~le in the rnass of rocks, it is advisable also to record variation o~ -the e~ectros-tatic polarization charOe of such an ore body, the subsequent excita-tion of the elastic waves being eI'-fected when ~the charge is at its maximumO
It is kno~Jn ~hat an elec~romag~etic pulse ra~iation appears in polymineral ore bodies under -the action o~ an elas-tic wave. The in-tensity o~ the electric ~ield at a distance of 1 m ~rom -the source o~ the elastic wave is reater than 107-1~8 ~/m and is higher than the in-tensit~
o~ piezoelectric, contact and seismoelectric field by a ~actor of hundreds and even thousands.
~ he charge rise time of the electrostatic polariza-tion and the relaxation time depend on mlneral composition o~
an ore body, The charge rlse -time ranges frcm several seconds to tens o~ seconds. ~he charge relaxation ~ime is s~veral mlnutes~
~ 11 polymineral bodies in a rock mass being studied a-re polarized whatever their thickness.
The amplitude of the electroma,~netic radiation pulses ge~erated u~der -the action o~ the elas-tic waves ~rom the polarized ore bodies is grea-ter than -the a~plitude o~
pulses o~ the electromagneti~ xadia-tion ge~era-ted by no~-polarized ore ~odies. At the moment at ~lhich the Glestro-sta~ic olariza-tion char~e o~ an ore body reaches its maximum value -the a,nplitude o~ the electromagnetic radia-tion induced by -the elastic l~aves excited in ~he rock mass at this momen-t increases b~ from 2 to 5 times deriendi~g on mineral composition of the ore body. ~his allo~s ~he electromagnetic radia~ion ~rom small-thickness ~re bodies and lrom ore bodies located at a substantial distance ~rom the point of recording o~ the electromagnetic radia~io~
to be recorded thus improving the accuracy o~ determi~ation o-f the ~umber o~ ore bodies in the rock mass being studied.
~ he invention will now be described ~ith re~erence to a speci~ic embodimen-t o~ a me-thod lor geophysical e~plora-tion of pol-Jmineral ore bodies illustrated in the accompan~ing drawin~s, in which:
Fi,ure 1 is a time char-t showi~g varia-tio~ ol -the electros-tatic polarization charge of ore bodies having the Oalenite-sphalerite composition, according to the invention;
~ igure 2 i9 a time chart showing variation o~ the electrostatic polarization charge of ore bodies o~ the ~uar-tz-an-timonite~ci~nabar composition;
Figure ~ i5 a time chart ~howing the electxomagne-tic pulse radia-tion.
A method fox geophysical exploration of polymineral ore bodies con.sists in the followi~g.
Elastic waves are exci-ted in a rock mass under study to induce an electromagnetic radiation and an elsct~os~ic polarization of ore bodies. For that ?urpose, an e~plo~ e charge is blown-up, the charge yield dependin~ on ~he -~olw~e o~ the rock mass bei~g s-tudied.
Exploration by -the method according ~o -the invention is mos-t ~requently conduc-ted in a mass o~ rocks rangin~ up to about 10~ m ~rom the p~in-t o~ explosionO ~he charge ~ield mainly depends on the conditions for the propagation ol ths elastic waves -through the mass o~ rocks under stud~, the mass size and mineral composition of ore bodies.
Generally the mass o~ a char~e~ e.g. o~ ammonite ohar~e does not exceed 6 ~g~ In applications vlhere the mass under s-tudy is small- irom 10 to 20 m, the elastic-waves can be excited by using non-explosive sources. An explosive cbarge is generally placed in the mou-th o~ an available borehole or in a recess at -the ~loor o~ a working.
The electros-tatic ~ield o~ polymineral ore bodies ma-ni~ests itsel~ in the ~orm of a posi-tive charge a-t their sur~ace~ and the time charts 1 (Figure 1) and 2 (~iæure 2) showing Yaria~ions o~ the charge ~or two deposits that have been investigated are given in the drawings, wherein the surface charge densit~ ~ in 10~9c~m2 is plotted on the ordinates a~d time in seconds is plotted on the abscissae.
By -the -time mome~t to~0 (be~ore the momen~ of explosion) there is a natural ch~rg~ o~ ore bodies with a sur~ace ~ensit~ ~ O (~ig. 1) and ~ O (Fi~ure 2). A~ter the explosio~ a charge rise occurs5 ~he time $max in which the charge attains its maxi~um value ~ max depending on mineral composition o~ an ore body and is about tma~=1 s for the galenite-sphalerite ore bodies (Figure 1) and about t~g=14 s for the quar~tæ-antimonite-cinnabar ore bodie~. The charge relaxation time is up to several minutes.
~ hen, during the time :Lnterval within which the electrostatic polarization of ore bodies still obtains, elastic waves are re-excited in the rock mass under s~ud7, e.O~. b~ blowing-up an explosive charge~ The seco,nd explosion i9 generally made adaacent -to -the point o~ the ~irst explo-sion~ at a distance precluding detonation o~ the explosive.
~he weiOh~ o~ the second explosive charge may be lo~er than that o~ the firs~ onec The second explosion can, e.g.
be made with an ammonite charge of 1 kgo The optimum time for the re-excitation o~ the elastic waves i9 the mome~t at which the value of the el~ctrostatic polarization charge achieves its maximum. In order to de-termine this time momen-t, an instrument for recording ~Jariation o~ -the electrostatic polarization charge, e.g.
an electro~eter with preriodical screeni~g o~ the measuring electrode i9 ins-talled in a known ore body undercut by a worki~g. By watchi~g 0~ the sereen of an electronic oscillo-soope or a like instrument varia~ion o~ the electrostatic polarizatio~ pote~tial, the maxi~um value of charge is visually determin~d and the re-e~citation o~ the elastic waves and recording o~ the electromagnetic pulse radiatio~
~3~
of -the ore bodies are e~ected at that moment, the nlmber o~ packe-ts o~ the radia-tion pulses determini~g the num'oer of polymineral ore bodies.
Figure 3 shows a time chart illustrati~, the diagram o~ the electroma~netic ~ulse radiation. The vol-tags U
in Volts at the output of' a recorder is plotted on the ordinates and time t in ms is plotted on the abscissae7 ~he ore body radia-tion is in the ~orm ol packets 3,4,5 o~
noise-like signals consisting o~ short pulses of different amplitude and polarity. ~hree packets 3, 4, 5 oY ~ulses can be seen on -the dia~ram ~rom which it follo~Js that in -the rock mass under study -three ore bodies worthy of co~mer-cial worki~g are discovered by t'ne method according to the invention.
For better understandinO o~ the in~-ention; the ~ol-lowing speci~ic example o~ its prac-tical realization is given belowq ~ he method ~or geophJsical exploration o~ polymineral ore bodies was tested on a deposit for prospecting ore bodies o~ the quar~tz-atimonite-cinnabar composi-tion. An electrometer ~or recording variation o~ the electrostatic polariza~ion charge o~ -the ore bod~ was installed on an ore body stripped by driving a worki~g. ~hen an ammonite charge o~ 4 kg was blown-up a-t one point o~ the working.
Under the aotion of an elastic wave caused by the explosion an electromagnetic radiation was genera-ted by ore bodies available in the rock mass under stud~, and _9_ variation o~ the electrostatic polarizatio~ charOe was recorded and visuall~ observed. At the mo~ent wnen ~he density of the electrostatic polarization charOe achis-Jed the maximum value of 6 _~.10 ~C/m2, a second explosion of an ammoni-te charOe o~ as made 14 s after the lrs.
explosion a-t a distance of about 1~ m from the poi~t of e~citation of the elastic waves by the ~irst charge. The ampli~ude of the electromagnetlc radiation pulses was 0.5; 1.3; 2.0 and 0.8 V ~or various objec-ts. ~herefore, four ore bodies were recorded in-the rock mass under study.
To determi~e the distance to a respec-tive ore body, t~ pulse arri~al time was also recorded. ~his -time was for -the above amplitudes ~.25; o.1; 1~.15; 14.1 ms, res-pec~ivel~.
Given the velocity of propaga-tion o~ the elastic wave through the county rock enclosing the ore body 7 -this distance could be easil~ found ~hus, with a velocity in solid limestones of 5.5 m/ms, ~he dis-tance -to the most remo-te ore body is 14 1 ms05.5 m/ms=78 m from the point of explosion In -the process of verification, these ~our ore bodies were actually undarcu-t by exploration boreholes.
For comparing the me~hod according ~o the inven-tion with the prior art method, the amplitude o~ pulses o~ -the elec-tromagne-tic radiation of ore bodies induced by the firs-t explosion was recorded. Three ore bodies were dis-coveredO ~he amplitudes o~ pulses were 0~1, 004; and 1 0 V, respectively, with their arrival -times 3~2; 6.1 and 1~.2 ms, respectively~ There~ore, the amplitude o~ the si~n31s emitted by the polarized oodies increased bJ a fac-tor ~ro~ 2 -to 5 so that an ore body could be discoverea tha-t had not been discovered after the ~irst explosion ~hen the ore bodies had no-t been polarized.
Claims (2)
1. A method for geophysical exploration of polymineral ore bodies, comprising:
- exciting in a rock mass under study elastic waves to induce an electrostatic polarization in ore bodies;
- subsequently exciting the elastic waves during the time interval within which the charge of said electrostatic polarization still exists;
- recording an electromagnetic pulse radiation generated by said ore bodies under the action of said elastic waves, the number of said ore bodies being determined by the number of packets of pulses of this radiation.
- exciting in a rock mass under study elastic waves to induce an electrostatic polarization in ore bodies;
- subsequently exciting the elastic waves during the time interval within which the charge of said electrostatic polarization still exists;
- recording an electromagnetic pulse radiation generated by said ore bodies under the action of said elastic waves, the number of said ore bodies being determined by the number of packets of pulses of this radiation.
2. A method for geophysical exploration of polymineral ore bodies according to claim 1, wherein, in case there is a known ore body in the mass of rocks, variation of said electrostatic charge polarization is recorded, said subsequent excitation of the elastic waves being effected after this charge achieves its maximum value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462982A CA1230404A (en) | 1984-09-12 | 1984-09-12 | Method for geophysical exploration of polymineral ore bodies |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000462982A CA1230404A (en) | 1984-09-12 | 1984-09-12 | Method for geophysical exploration of polymineral ore bodies |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1230404A true CA1230404A (en) | 1987-12-15 |
Family
ID=4128699
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000462982A Expired CA1230404A (en) | 1984-09-12 | 1984-09-12 | Method for geophysical exploration of polymineral ore bodies |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1230404A (en) |
-
1984
- 1984-09-12 CA CA000462982A patent/CA1230404A/en not_active Expired
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