SU1509135A1 - Method of tuning radiometric separator for grading lump mineral initial materials - Google Patents

Abstract

The invention relates to the separation of ore raw materials and allows you to quickly and with high accuracy set the required threshold of the threshold separator stage (C) and, accordingly, the separation mechanism. The threshold is set by the test signal, which is formed by modulating the signal arriving at the measuring path from the reference piece. The modulating signal is formed as a sequence of trapezoidal voltage pulses with intervals between pulses D / V (C) and H-D / 2V (C) fronts duration, where H and D are the lengths of the lower and upper bases of the radiation pattern of the sensitive element C, m

V is the speed of the pieces of raw material in the measurement zone C when sorting, ms ^-1 . The amplitude of the pulses of the modulating signal is formed equal to the magnitude of the discrimination voltage at which the pulse counting rate at the output when the reference piece located in the measurement zone is reduced to the count rate from the natural background. The modulation is performed by applying a modulating signal, thereby changing the discrimination level periodically, as a result of which a test signal arrives at the threshold cascade, which is adequate to the signal from the reference piece during sorting. 5 il.

Description

The invention relates to the mining and processing industry of the national economy and can be used in the radiometric enrichment of raw materials, the separation of which is the value of natural radioactivity or the intensity of scattered radiation.

The purpose of the invention is to increase the tuning accuracy by approximating the shape of the modulated signal to the shape of the real signal in the light from the piece under study.

FIG. Fig. 1 shows the directivity pattern of the separator detector (in - the distance from the center of the piece to the axis passing through the center of the detector perpendicular to its sensitive surface, m; J - pulse count rate, them-s; Fig. 2 - block diagram of the measuring path separator with devices connected to it, used when adjusting the separator, in Fig. 3 and 4 are oscillograms of signals at points a and b of the circuit, respectively, during tuning, and Fig. 5 is an envelope of the average pulse counting rate at a point in the scheme.

The measuring path of the separator (Fig. 2) contains a radiation detector 1 connected in series, an amplifier 2 pulses, an integral amplitude discriminator 3, a normalizer 4 pulses, a recorder 5, a threshold stage 6, a separation mechanism 7. A generator 8 is connected to the circuits of the measuring path for tuning

cl

about

from the next

trapezoidal pulses, voltmeter 9, switch 10, scaler 11.

The method of setting up the separator consists in setting the reference piece in the measurement zone of the separator, recording the radiation intensity and converting it into a pulsed electrical signal, generating a sequence of pulses and modulating the pulsed electrical signal and modulating the separator trigger signal, and generating pulses in the sequence of the modulating signal trapezoidal shape with a duration of fronts equal to

t- - with

.with,

where / g NA / - the length of the lower and upper bases of the radiation pattern of the sensitive element of the separator; V - the rate of pieces of raw materials in the zone

measurements.

and the amplitude of the pulses is set equal to the intensity of discrimination, in which the counting rate of pulses of a pulsed electrical signal corresponds to the counting rate from a natural background, and the interval between pulses is equal to

/ - with / --- with

The method is carried out as follows: With the help of a scaling device 11 (Fig. 2) connected via switch 10 to the output of the normalizer 4, the counting rate of pulses Jq is determined in the absence of pieces of raw material in the separator measuring zone, i.e. pulse count rate from natural radioactive background. Then a reference piece of raw material is installed in the measurement zone and the pulse count rate e is also recorded. After that, not removing the piece from the measurement zone, increase (for example, by changing the position of the variable resistor R in the discriminator 3) discrimination level of the discriminator 3 until the counting rate is equal to the Jiis value and the voltage Ugfi is fixed at 9 which is used in the future as the amplitude of the pulses of the modulating SIR nal. Then, the level of discrimination is reduced to the initial value and the definition of the directivity pattern of the separator detector (if it is unknown) is taken up. For this, the reference piece of raw material is moved in the zone of measurement of the separator with a certain tag, and the distance in from the center of the piece to the axis passing through the center of the detector is fixed to its axis.

sensitive surface, and simultaneously register the count rate J of pulses at the output of the normalizer 4 at each position of the piece. According to the data obtained, a graphical dependence of J / (b) is constructed, i.e. The directivity pattern of the detector, the nature of which in its general form is represented by the dotted curve in FIG. 1. The radiation pattern is extrapolated to the trapezoid, highlighted by flat lines in FIG. 1. Determine the value of the lower base of the trapezoid h, m and the upper one - d, M. According to the values of h, d and the velocity V of the pieces in the measurement zone, when they are sorted, the values of values of and, c, which are used

when forming the edges of the pulses of the modulating signal and the intervals between the pulses, respectively.

Then move on to setting up the separator. For this, using a generator 8, a sequence of pulses (Fig. 4) is formed of a trapezoidal shape with an amplitude of pulses equal to UgB, the duration of fronts

5, with intervals between impulses

themselves in the sequence, and the period T of the pulse following in the sequence equal to the average time

Q interval between pieces of raw material when passing them through the separator in the process of sorting. The generated pulse sequences are fed to the discriminator 3 (as shown, for example, in FIG. 2), thereby changing the level periodically

5 discrimination discriminator. After that, a reference piece of raw material is installed in the center of the separator measurement zone, the intensity of radiation from it is recorded by the detector 1 of the separator and converted into a pulsed electrical signal.

0 which is amplified by the amplifier 2 of the measuring path of the separator, and amplified is fed to the input of the discriminator (Fig. 3). The amplitude of the pulses entering the discriminator input is different (except for

from separators, in which Geiger counters and ionization chambers are used as detectors, which are practically not used, since they have low efficiency compared to scintillation counters.

0 Since, under the action of the sequence of the pulses of the modulating signal, the discrimination level of the discriminator 3 periodically changes, only those electric signal pulses are passed to its output at each instant of time, the amplitude of which is higher than the discrimination level at the same time, i.e. on the discriminator, an amplitude modulation of a pulsed electric signal by a sequence of pulses of a modulating signal occurs. As a result, at the output of the discriminator 3, the pulse counting rate of the pulsed electrical signal changes in time and the envelope average pulse counting rate looks as shown in FIG. 5, i.e. the modulated signal is a sequence of pulse bursts, a voltage with a burst frequency of 1 / T, in which the frequency J of pulses over time

/ ,, increases from 7f tr

to / e and remains constant for a period of time, after which it drops from

Js up to 7f for the time interval equal to the time equal to / 3 and remains equal to the next burst, i.e. The modulated signal is adequate to the input to the recorder and the threshold cascade of the measuring path of the separator from the reference pieces of raw material in the process of their sorting. Then, the modulated signal is passed through the normalizer 4 and the recorder 5 to the input of the threshold stage 6, and changing the threshold level of the threshold stage and simultaneously counting the frequency of operation (for this purpose, the scaling device 11 is connected to the output of the threshold stage 6) , the trigger frequency of the threshold cascade is adjusted (which is adequate to the trigger frequency, separate the mechanism) to a predetermined value, which is usually 0.5 1 / T, i.e. 2 times lower pulse frequency in the modular signal.

0

five

0

five

0

Claims (1)

Invention Formula The method of tuning the radio. Is from a separator of a piecewise sorting of mineral raw materials, consisting in that the reference piece is installed in the measurement zone of the separator, the radiation intensity is recorded and converted into a pulsed electrical signal, a pulse sequence is formed and modulated by them The electric signal is also modulated and has the threshold for the operation of a separator), which differs in that. what, with the price. In order to increase the accuracy of tuning by approximating the shape of the modulated signal to the shape of a real c1 G} 1al, perceived from the test piece, the pulses are sequentially modulated by ciH na. ia form trapezoidal shape. we with D. 1.1.1nostnost fronts t, paBHoii - i where / i d are the lengths of the lower and upper bases of the loading diagram of the sensitivity of the sensitive element of the separator; L speed of pieces of raw materials in the zone separator measurement with an amplitude equal to the d.cryption voltage, at which the count rate is im iiNniy. ibCHoro elsktricheskogo signal corresponds to the count rate from the natural background, and the interval. / mezh.gu i.mpu.1'- equal to -four ag 7 faz.Z .З Jjjii