RU2356651C1 - Method of roentgen-luminescent separation of minerals - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention refers to concentration of minerals, particularly to methods of roentgen-luminescent concentration of crushed mineral material of coarse fractions, size of which is comparable with length of zone of excitation-recording of separator. To achieve the said excitation of luminescence of minerals is performed with pulse roentgen radiation (PRR), further summary intensiveness of short component of luminescence (SCL) and prolonged component of luminescence (PCL) are measured at the moment of PRR operation; intensiveness of PCL is measured with delay after termination of PRR operation; values of ratio of summary intensiveness of SCL and PCL to intensiveness of PCL are determined and compared to a threshold value; further minerals are separated according to assumed determination. Also luminescence of minerals is excited with at least two PRR. At each pulse of PRR value of intensiveness of PCL is compared with preset threshold value and value of ratio of summary intensiveness of SCL and PCL to its intensiveness of PCL is recorded. Notably, value of above said ratio is accepted as equal to zero, if value of intensiveness of PCL is less, than the threshold one. Value of difference between current and preceding values of ratio of summary intensiveness of SCL and PCL to intensiveness of PCL is determined and determination "useful mineral" is assumed, if value of ratio of summary intensiveness of SCL and PCL to intensiveness of PCL is less, than preset threshold value and if simultaneously all values of difference between current and preceding values of above said ratio are positive.

EFFECT: upgraded selectiveness of roentgen-luminescent separation of minerals of coarse grades due to avoiding false extraction of associated minerals and consequently increased contents of useful mineral in concentrate (upgrading of condition).

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Description

The invention relates to the field of mineral processing containing luminescent minerals under x-ray radiation, and in particular to methods for enriching crushed mineral material of large fractions, the size of which is comparable with the length of the excitation-registration zone of the separator. Such a method can be used both in X-ray luminescent separators at all stages of enrichment, and in production control devices, for example, diamond-containing raw materials.

In X-ray fluorescence separation, the property of minerals to generate radiation in the optical region of the spectrum under the influence of X-ray radiation is used. When the stream of enriched material is irradiated with periodic pulses of X-ray radiation, some minerals transported through the exciter-registration zone of the separator luminesce. Moreover, both the intensity and kinetic characteristics of luminescence depend on the type of mineral.

To increase the selectivity of the extraction of the enriched mineral in the known methods of X-ray fluorescence separation, the kinetic characteristics of the luminescence signal are used, recorded both during and after exposure to X-ray radiation. The kinetic characteristics of the luminescence of the mineral have at least two luminescence components, which differ in the time constant of the rise and fall of the luminescence. The short component has a time constant at the fraction of microseconds, and the time constant of the long component lies in the range of (0.5-20) ms.

For example, there is a known method of separation of minerals (SU 1603588 A1 B07C 5/342, 08.20.1999.), Which includes irradiating the starting material with X-ray pulses to excite the luminescence of a useful mineral, measuring the intensities of the short and long components of the luminescence excited in it and extracting the useful mineral from the original material for a given ratio of measured intensity levels, selected as a separation criterion. In this case, the intensity levels are measured during the exciting pulse I ₁ and with a delay relative to the exciting pulse - I ₂ , and the separation of minerals is carried out, for example, when the relation

I ₂ / (I ₁ -I ₂ ) <0.17.

In this method, the intensity of the short luminescence component is determined by subtracting I ₂ from the total luminescence intensity I ₁ measured during the exciting pulse, that is, the contribution of the long component is taken into account. However, with this separation method, it is very difficult to obtain the minimum necessary measurement error, which negatively affects its selectivity.

Also known is the prototype method for the separation of diamond-containing materials (RU 2235599 C1 B03B 13/06, B07C 5/342. 09/10/2004), including the excitation of luminescence of minerals by pulsed x-ray radiation of sufficient duration to ignite the long-term luminescence component, measure the total intensity of short and the long-term component of luminescence at the time of the action of the x-ray pulse, measuring the intensity of the long-term component of luminescence with a delay after the end of the action of the x-ray pulse th radiation, determining values of the ratio of the total intensity short and long luminescence component I ₁ = I _a + I _d to the intensity of delayed luminescence components I _2, comparing it with a threshold value and separating the desired mineral from the comparison result. If the value of the ratio I ₁ / I _{2 is} less than the threshold, then a decision is made that the mineral is “useful”, and if I ₁ / I _{2 is} greater than the threshold, then the mineral is considered “concomitant.

This method can give good results on the separation selectivity at a constant position of the mineral in the excitation-recording region of the luminescence, since in this case the value of the ratio adopted as the separation criterion does not change upon sequential irradiation of the mineral with several x-ray pulses. However, the luminescent mineral moves with the material and enters the excitation-recording zone of luminescence asynchronously with respect to the excitation pulses. In the separation of mineral material of large fractions, when the size of the mineral is comparable with the length in the direction of the material flow of the excitation-registration zone, the effect of false detection of a “useful mineral” appears. Consider this effect in relation to a concomitant mineral for which the I ₁ / I ₂ value is greater than the threshold. As the mineral moves through the excitation-registration zone, the measured value of the long-term luminescence component) s somewhat increases, but the value of the ratio I ₁ / I ₂ remains greater than the threshold value. Therefore, a mineral is defined as "concomitant." But at the exit of the mineral from the excitation-registration zone, the intensity of the short component) k decreases sharply, and the value of the ratio I ₁ / I ₂ also decreases and becomes less than the threshold. As a result, when a mineral leaves the excitation-registration zone, the same mineral is falsely defined as “useful” and is separated into a concentrate, which reduces the selectivity of separation.

The technical result of the invention is to increase the selectivity of the process of x-ray luminescent separation of large-class minerals by eliminating the false extraction of related minerals and, as a result, increasing the useful mineral in the concentrate (improving condition).

Achieving the technical result provides the proposed method of x-ray luminescent separation of minerals, including the excitation of luminescence of minerals by pulsed x-ray radiation of sufficient duration to ignite the long component of the luminescence, measuring the total intensity of the short and long component of the luminescence at the time of the x-ray pulse, measuring the intensity of the long component of the luminescence with a delay after completion X-ray pulse action about radiation, determining the value of the ratio of the total intensity of the short and long luminescence components to the intensities of the long luminescence components, comparing it with a threshold value, making a decision “useful mineral - an accompanying mineral” and separating the minerals according to the decision in which the luminescence of minerals is excited, at least , with two pulses of x-ray radiation, at each pulse of x-ray radiation, the intensity value of the long-term component of the luminescence is compared and with a given threshold value and remember the value of the ratio of the total intensity of the short and long components of the luminescence to the intensity of its long component, and the value of the above ratio is zero, if the value of the intensity of the long component is less than the threshold, determine the difference between the current and previous values of the ratio of the total intensity of the short and the long-term component of luminescence to the intensity of its long-term component, and decide "beneficial mineral", e if the value of the ratio of the total intensity of the short and long components of luminescence to the intensity of its long components is below a given threshold value and at the same time all the values of the difference between the current and previous values of the above ratio are positive.

In contrast to the known method in the proposed method, the luminescence of minerals is excited by at least two x-ray pulses, with each x-ray pulse, the intensity value of the long-term luminescence component is compared with a predetermined threshold value and the value of the ratio of the total intensity of the short and long-term luminescence components to its long-term intensity is stored components, and the value of the above ratio is zero if the intensity value of the long-term comp entes less than the threshold, determine the difference between the current and previous values of the ratio of the total intensity of the short and long components of luminescence to the intensity of its long-term component, and decide "useful mineral if the value of the ratio of the total intensity of the short and long components of luminescence to the intensity of its long-term component is lower than the specified threshold value and at the same time all values of the difference between the current and previous values of the aforementioned relationship - polo living.

The combination of distinctive features and their relationship with restrictive features in the present invention provides the selectivity of the separation of minerals of large fractions. In the proposed method, the solution is “useful mineral”, for which the ratio of the total intensity of the short and long components to the intensity of the long component of the luminescence is in the range of specified values, is taken not according to the results of determining this ratio after the next exciting pulse, but taking into account the history of changes in this ratio after “ n ”of previous pulses.

Figure 1 presents the timing diagrams:

a - excitation pulses (conditional serial numbers 1 ... 5),

b - signals for recording the luminescence of a useful mineral;

c - signal for separation of a useful mineral;

g - signals for recording the luminescence of the associated mineral.

Figure 2 presents the structural diagram of the separator for the implementation of the proposed method of x-ray luminescent separation of minerals.

When implementing the proposed method for the separation of minerals, a corresponding threshold value (U _s / U _d ) _p (not marked in FIG. 1) is preliminarily set for the ratio of the total intensity U _{s of the} short and long-term component of the luminescence of the mineral to the intensity U _{d of} its long-term component and the threshold value U _p the intensity U _{d of the} long-term component of the luminescence of the mineral (figure 1). The luminescent mineral moves with the enriched material and enters the luminescence excitation-registration zone. As the mineral moves through the excitation-registration zone, it is irradiated with periodic pulses of x-ray radiation with conditional serial numbers 1 ... 5 (figa). The pulse duration _and t must be such that the time to ignite a long luminescence signal component of useful mineral.

Consider the luminescence signal of a useful mineral (figb). After exposure to pulses (figa) with numbers 1 and 2, until the mineral entered the excitation-registration zone, there is no signal of intensity U _{d of the} long-term luminescence component (below the threshold U _p ), therefore, the value of the ratio U _s / U _{d of the} total intensity U _{s of} luminescence of the short and long components to the intensity U _{d of the} long component is remembered as zero. After the action of the excitation pulse 3, the luminescence signal of the useful mineral from the intensity U _{d3 of the} long-term component (determined through the interval t ₁ from the beginning of the excitation pulse t ₀ ) exceeds U _p , and the ratio U _s3 / U _{d3 of the} total luminescence intensity of the short and long components to the intensity of the long-term component lies in the range of preset values U _s3 / U _d3 <(U _s / U _d ) _p (i.e., below the threshold value), and the difference values U _s3 / U _d3 -U _s2 / U _d2 and U _s3 / U _d3 - U _s1 / U _d1 between the current and two previous (to simplify the description n = 2) values the ratios of the total luminescence intensity of the short and long components to the intensities of the long component are positive, i.e. (U _s3 / U _d3 -U _s2 / U _d2 )> 0 and (U _s3 / U _d3 -U _s1 / U _d1 )> 0. Therefore, the separation of the useful mineral from the enriched material is performed - a signal is issued to the separation (pigv). As can be seen from the diagram (fig.1b), further relations for the luminescence signal of a useful mineral when moving along the excitation-registration zone with subsequent pulses 4 and 5 do not affect the separation.

In the case of passing through the excitation-registration zone of the associated mineral (Fig. 1d) after exposure to excitation pulses 1 and 2, there is no signal of intensity U _{d of the} long-term luminescence component

(below the threshold U _p ), therefore, the value of the ratio U _s / U _{d is} also stored as zero. After exposure to excitation pulses 3 and 4, where the intensities U _d3 and

U _{d4 of the} luminescence of the long-term component exceeds U _p (U _d3 > U _p and U _d4 > U _p ),

values of U _s3 / U _d3 and U _s4 / U _d4 ratios above their threshold value

(U _s3 / U _d3 > (U _s / U _d ) _p and U _s4 / U _d4 > (U _s / U _d ) _p ). The obtained values of U _s3 / U _d3 and U _s4 / U _{d4 are} memorized, but no signal is given to separate the mineral. After the action of the excitation pulse 5, when the accompanying mineral leaves the excitation-registration zone, the value of the ratio U _s5 / U _{d5 is} lower than the threshold value (i.e., lies in the range of preset values

U _s5 / U _d5 <(U _s / U _d ) _p ) because of that. that the short component is no longer “visible”. However, the signal to separate the accompanying mineral, which after the excitation pulse 5 has the characteristics corresponding to the useful mineral, does not give out, since the values of the difference U _s5 / U _d5 -U _s4 / U _d4 and U _s5 / U _d5 -U _s3 / U _d3 between the current and previous stored values of the ratio of the level of the total luminescence intensity of the short and long components to the intensity level of the long component is negative ((U _s5 / U _d5 -U _s4 / U _d4 ) <0 and

(U _s5 / U _d5 -U _s3 / U _d3 ) <0).

Thus, an additional sign of diamond is an increase in the ratio ((U _si / U _di -U _sk / U _dk )> 0, where i = 1, 2, 3, (k + 1) and k = 1, 2, ... (i -1)) of the total luminescence intensity of the short and long components to the intensities of the long components, and the associated mineral - a decrease in this ratio ((U _si / U _di -U _sk / U _dk ) <0) at previous pulses. By analyzing the history, it is possible to exclude the false detection of large associated minerals, which, when moving along the excitation-registration zone, are affected by two or more excitation pulses.

The separator (figure 2), which implements the proposed method, comprises a hopper 1 with enrichable material, a feeder 2, a conveying device 3 in the form of an inclined tray, a pulsed x-ray source 4 with an x-ray tube, a photodetector 5, a luminescence signal processing unit 6 , a cut-off unit 7 with an actuator (not shown in FIG. 2), a concentrate accumulator 8 and a tail removal line 9.

Hopper 1, feeder 2, pulsed x-ray source 4, photodetector 5, cut-off unit 7, concentrate storage 8 and tail tailing line 9 can be performed, for example, as in the separator LS-D-4-03 (Operation manual for the fluorescent separator LS-D-4-03, St. Petersburg, 1997). Processing unit 6 contains a logarithmic amplifier, a device for sampling and storing the UVX for storing the values (on a logarithmic scale) of the total signal U _s and the signal U _{d of the} long-term component, analog adders to determine the ratio (difference of logarithms) of the values of the total signal U _s and the signal U _{d of} long components, I / O for storing the indicated relations in n-cycles and a comparison device (in the form of analog adders) of the values of the said relations in the current and previous cycles. The input of the amplifier serves as the input of block 6, and its output is connected to the inputs of the device for sampling and storage of the UVC. The number of UVC is (2 · n), where n is the number of cycles of historical analysis. The outputs of the I / O are connected to the inputs of the analog adders.

A logarithmic amplifier can be performed, for example, as described in the literature (E.A. Colombet. Microelectronic means for processing analog signals. M: Radio and communications, 1991, p. 102, table 4.3.). An analog adder can be performed, for example, as described in the same literature, p. 96, fig. 4.20. UVC can be performed, for example, as described in the same literature, p. 225, table 8.1a.

The separator works as follows. The hopper 1 is filled with an enrichable material, for example diamond-containing, in the signal processing unit 6, a threshold value (U _s / U _d ) _{p of the} ratio of the total intensity U _{s of the} short and long luminescence component to the intensity U _{d of} its long-term component and the threshold value U _{p of the} intensity of the long-term component are entered . After turning on the feeder 2, the material begins to flow through the transporting device 3 into the excitation-recording zone (not shown in Fig. 2), where it is exposed to pulses (Fig. 1a) of X-ray radiation from source 4. The value of t _{and the} duration of the excitation pulse is 0.5 ms. The period T = 4 ms following the excitation pulses is comparable with the lifetime of the long-term component of a useful mineral - diamond. During the passage of the excitation-registration zone, pieces of material are exposed to several radiation pulses (Fig. 1) from source 4. The resulting luminescence of diamonds and related minerals is perceived by the photodetector 5. The electrical signal that occurs in the device 5. enters the signal processing unit 6 . In block 6, a determination is made of the value of the total luminescence intensity U _{s of the} short and long components during the action of the pulse t _and excitation, the values of the luminescence intensity U _{d of the} long component after a specified time t ₁ after the end of the pulse t _and excitation and the value of the ratio U _s / U _d , compare the obtained values of U _d and U _s / U _d with the given threshold values of these quantities, for each excitation pulse, remember the values of the ratio U _si / U _di ), where i = 1, 2, 3, (k + 1), and determine the values differences (U _s / U _d -U _{s (ik)} / U _{d (ik)} ) between the current value of the ratio U _si / U _di and the stored values of U _{s (ik)} / U _{d (ik)} , where k = 1, 2, ... (i-1), of this ratio. When the combined condition is fulfilled: the intensity U _{d of the} long-term component is above a given threshold U _p and the ratio

U _si / U _di <(U _s / U _d ) _{p the} total luminescence intensity of the short and long components to the intensity level of its long components below a given threshold and the difference (U _s / U _d -U _{s (ik)} / U _{d (ik)} )> 0 between the current value of the ratio U _s / U _d and “n” by the previous values of this ratio — positive — a signal is issued to block 7 to separate the mineral from the rest of the material. When the actuator actuates, the diamond is separated into the concentrate accumulator 8, the rest of the material falls into the tailing line 9.

For large associated minerals, the condition of a positive difference

(U _s / U _d -U _{s (ik)} / U _{d (ik)} )> 0 between the current U _si / U _di and the “n” previous values

U _{s (ik)} / U _{d (ik)} , the total luminescence intensity of the short and long components to the intensity level of the long component is not fulfilled (in this case (U _s / U _d -U _{s (ik)} / U _{d (ik)} ) < 0) and large associated minerals in concentrate 8 are not separated.

Thus, the proposed method of x-ray luminescent mineral separation allows to increase the selectivity of the separation of large classes of minerals by eliminating the false extraction of related minerals and, as a result, to improve the condition of the concentrate.

Claims (1)

A method for X-ray luminescent separation of minerals, including excitation of luminescence of minerals with pulsed X-ray radiation of sufficient duration to ignite the long component of the luminescence, measuring the total intensity of the short and long component of the luminescence at the time of the x-ray pulse, measuring the intensity of the long component of the luminescence with a delay after the end of the x-ray pulse, determination of the value of the ratio of total intensive the short and long component of luminescence to the intensity of the long component of luminescence, comparing it with a threshold value, making a decision “useful mineral - accompanying the mineral” and separating the minerals according to the decision, characterized in that the luminescence of the minerals is excited by at least two x-ray pulses , at each x-ray pulse, the intensity value of the long-term luminescence component is compared with a predetermined threshold value and the value is stored the ratio of the total intensity of the short and long components of luminescence to the intensity of its long component, and the value of the above ratio is assumed to be zero, if the value of the intensity of the long component is less than the threshold, determine the difference between the current and previous values of the ratio of the total intensity of the short and long components of luminescence to its intensity long-term components, and make the decision “beneficial mineral” if the value of the ratio of the total intensity The likelihood of the short and long components of luminescence to the intensity of its long components below a predetermined threshold value, and at the same time, all values of the difference between the current and previous values of the above ratio are positive.

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