The method of determining the safety of diamonds in the technological processes of processing

 

(57) Abstract:

Usage: the invention relates to the beneficiation of minerals. The inventive method includes the selection of a representative sample of diamonds, calculating the average weight of the crystal in the sample, determining for each crystal in the sample polarized light, which characterizes the magnitude of the stresses in the crystal, the distribution of crystals in polarized light, calculate the average and standard deviation of the intensity of polarized light and the assessment of the degree of preservation of diamonds by the formula where Icf.- the average value of the intensity of polarized light; Pcf.- the average weight of the crystal in the sample; - the standard deviation of the intensity of polarized light. 3 Il., table 1.

The invention relates to the beneficiation of minerals, and in particular to methods of assessing the safety of diamonds in the processes of extraction and processing.

There is a method of assessing the safety of diamonds in technological treatment processing plants, based on the visual comparison of the damage of the crystals from the current mining and diamond-indicator introduced in technological processing. The essential substance of sdelaetsja the following groups: integer, whole with cracks and inclusions, a little disturbed, much broken shards.

The determination of the degree of disturbance of the crystals is done visually using a microscope.

To slightly disturbed crystals are those, which, according to subjective evaluation mineralogist, missing 10 15% mass of the whole, to significantly disturbed crystals that make up more than half of the whole, to fragments less than half of the whole crystal.

Similar mineralogical description of a very long process, which can produce only a specialist with extensive experience. The assessment of the degree of disturbance is complicated by the fact that many of the crystals have an irregular shape (flattened, elongated, indeterminate forms), so often one and the same crystal of different experts attribute in different categories depending on their subjective perception of the degree of integrity. An additional and very important complication of difficulties that arise in mineralogists in the analysis chips on the crystals.

If the fracture occurred in the natural environment, as a rule, during the growth of diamond or transporting it kimberlite masses to the Earth's surface, such chips, as a rule, there is ryznicami fracture are considered to be "man-made".

Clear criteria differences in the sculptures there, so depending on the qualifications of the expert crystal with chip for this reason can get both in the number of whole and in the bad.

Subjective evaluation introduces a large error in the determination of the degree of preservation, and mineralogical description of the crystals is time consuming.

There is a method of determining the safety of diamonds in the product processing plants, including the selection of a representative sample of diamonds from each size class, the identification of each of the crystal morphology of the damage and assess the degree of preservation of the relative amounts of diamonds with damage to the total number of diamonds in the sample [1]

This solution does not correct the deficiencies noted in the criticism of the similar.

The technical problem of the invention increase the accuracy and timeliness of the assessment of the safety of diamonds.

This object is achieved in that in the method of determining the safety of diamonds, including the selection of a representative sample of diamonds, the definition of each crystal of a given diagnostic indicator and assessment of the safety of diamonds, determine the average weight of the crystals (Pis the order of stresses in the crystal, build the distribution of crystals in polarized light, calculating the mean value and the standard deviation of the intensity of polarized light, assess the safety of diamonds by the formula

< / BR>
where Icf.the average value of the intensity of polarized light;

the standard deviation of the intensity of polarized light.

The proposed method is illustrated in Fig. 1 3.

When creating inventions came from the following theoretical and experimental prerequisites.

In connection with thermodynamic conditions of crystal growth in their volume generated local area stress, manifested from the point of vacancies to macro defects. Natural collection diamond has lognormal distribution on the stress value. Because the crystals with large stress values are destroyed in the first place, then the probability of their destruction at the same mevastatin significantly higher compared to other crystals. As a result of the process the crystals with large stress values are destroyed more frequently and on the release of their contribution to the overall set of diamond decreases. The graph is b the th values, and the reduction of the "tail", i.e. values with large values of stresses at fracture or lose tension, or a few pieces with residual or induced again stresses (see Fig. 2A, B).

Thus, the average value is an important parameter in the safety of the crystals. The lower average value of the tension, the lower the integrity of the diamond.

The intensity of polarized light passing through the crystal is proportional to the tension in the crystal. This is because the natural light passing through the first polarizer becomes linear polarization and becomes linearly polarized light. Linearly-polarized light passing through the crystal rotates the plane of polarization by an angle directly proportional to the presence of stresses in the crystal. The second polarizer transmits only the portion of the linearly-polarized light which is deviated from the plane of polarization, i.e., transmits polarized light, is proportional to the tension in the crystal.

Knowing the intensity of each crystal individually, can be functions of the relative frequency of the crystal in the sample from strength values. Knowing prirodoohrany process. Because all values have a relative, we are interested in only the shape of the curve and not its absolute value.

Another important parameter reflecting the shape of the curve, the distribution of the average value and the standard deviation or variance, which indicates the amount of variation in stress intensity. If a portion of the crystals with large stress values collapsed, and the average value will decrease (shift of the maximum of the distribution curve), but the standard deviation is either not change, or changes very little.

Therefore, the closer the obtained distribution curve of crystals in polarized light (after passing process technology ) will be the natural lognormal distribution, the greater the safety of the process.

The recorded intensity of the polarized light is proportional to the crystal volume. To get rid of dependence on the indications of preservation from the size entered normalizing factor, dependent on the volume (size) and, therefore, the thickness of the crystal, it is the weight of the crystal in the sample. Because we are interested in the preservation of the sample as a whole, then the average weight of the crystal sample.

An example of a specific implementation.

For a particular implementation of the method, we selected 1000 transparent crystals of size -3+2 mm produced using blast and combine method.

Was created the device (Fig. 1), designed to measure the crystals polarized light, characterizing the tension. The device consists of the illuminator 1, crossed polarizers 2, a collecting lens 3 and measuring the intensity of light 4, which includes an amplifier and recording device. As the illuminator 1 was used incandescent lamp power 20 W, fed by a stabilized power supply with a voltage of 8 V and a coefficient. stabilization 30.

One of the polarizers 2 is mounted in a swivel clip to adjust the instrument in the absence of crystal for minimum signal. As of 4 meter light intensity was used for the photodiode PD-3 preamplifier, nahc performed on low-noise OY K ODA and enabled by reinvestiruja scheme. In front of the photodiode in the path of the beam placed collecting lens designed to focus the light beam on the photodiode. Photodiode, preamplifier, and a collecting lens can be moved in the vertical direction for adjustment of the device.

As the recording device can be used by any voltmeter with sufficient accuracy. In our case we used universal digital voltmeter 7 16.

Each of the diamonds of both parties were placed between the polarizers 2 and measured the intensity of polarized light passing through the second Polaroid and characterizing the integrated intensity in each sample of the diamond.

The data obtained were entered into a computer and using the SPT "Statgraphic" built distribution of crystals (Fig. 3) in each batch according to the degree of intensity (intensity of anomalous birefringence). Both parties diamonds were weighed and calculated the average weight of the crystals according to the formula

< / BR>
where mithe weight of the i-th crystal;

N, number of diamonds in the party.

The average value of the distribution when the explosion was 0,0400 with a standard deviation 0,044 and at the combine production average value of the VA is slightly higher albeit only slightly. The average weight of the crystals was when explosive and combine production, respectively 0,244 CT and 0,216 CT.

Then carried out the assessment of the safety of diamonds by the formula

< / BR>
where Icf.the average value of the intensity of polarized light characteristic of the average strain in the crystals;

the standard deviation of the intensity of polarized light;

Pcf.the average weight of the crystal.

The result is a performance security: for party, extracted "explosive" method S 3,725 for the party obtained through the harvester's 1,158.

The analysis of the degree of disturbance of these crystals by the method of the prototype gave the results presented in the table.

Both methods showed higher security of crystals in the extraction using the harvester, but unlike the prototype method required two mineralogists during the week, the data measured and processed by the present method were obtained on the same day. Besides winning time eliminates the subjectivity of the evaluation, since all measurements are made instrument methods. Unlike the prototype method, which does not give an explicit quantitative evaluation of preservation, and shows sub is the IR.

The method of determining the safety of diamonds in the technological processes of processing, including the selection of a representative sample of diamonds, the definition of each crystal of a given diagnostic indicator and assess the degree of preservation of diamonds, characterized in that to determine the average weight of crystals in the sample, determine for each crystal the intensity of polarized light, which characterizes the magnitude of the stresses in the crystal, build the distribution of crystals in polarized light, calculating the mean value and the standard deviation of the intensity of polarized light, assess the degree of preservation of diamonds by the formula

< / BR>
where Jcfthe average value of the intensity of polarized light,

Pcfthe average weight of the crystal in the sample,

the standard deviation of the intensity of polarized light.

 

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