Processing analysis method for coarse-grain-containing gold ore sample

Abstract

The invention discloses a processing analysis method for a coarse grain-containing gold ore sample. The processing analysis method comprises the following steps: step 1, crushing, screening, uniformly mixing and splitting the coarse grain-containing gold ore sample; 2, fine crushing and heavy sand separation are conducted, and a heavy sand sample and a light mineral sample are obtained; 3, the heavy sand sample is subjected to wet digestion analysis, and the gold content is measured; 4, processing the light mineral sample, and determining the gold content; and 5, calculating the gold content of the coarse-grain gold ore sample. According to the method, natural gold is separated and enriched from the sample through heavy sand separation, the situation that large-particle-size natural gold is difficult to disperse uniformly in the machining process is avoided, the precision and accuracy of the gold content detection result are improved, then the heavy sand sample is subjected to wet digestion analysis, the roasting process is removed, the natural gold loss risk is reduced, and the detection accuracy is improved. Finally, the weighted average value of the gold content of the heavy sand sample and the light mineral sample is used as the gold content of the coarse-grain-containing gold ore sample, the determination precision is improved, and the method is suitable for the technical field of mineral processing analysis.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing analysis, and particularly relates to a processing and analysis method for a coarse-grained gold ore sample. Background Art

[0002] Gold ore refers to the gold-containing ore mined from a mine manually or mechanically. Gold in gold ore mainly exists in the form of native gold, often in irregular granular, massive, flaky, reticular, dendritic, fibrous and spongy aggregates. When the proportion of native gold with a particle size of 0.07 mm - 0.3 mm in gold ore reaches 20% or the proportion of native gold with a particle size of 0.3 mm - 0.5 mm reaches 10%, it is called coarse-grained gold ore.

[0003] In order to detect the true grade of a gold deposit, chemical analysis of the ore sample must be carried out. First, the gold ore sample is crushed. Generally, the gold ore sample is required to be processed to a particle size less than 0.074 mm. Due to the high ductility of native gold in coarse-grained gold ore, there is a large difference in the degree of crushing with gangue minerals, and it is not easy to be further pulverized. Native gold grains often roll into spherical or cigar-shaped, and the particle size will not be significantly reduced. And the existing processing and analysis process of gold ore samples is as follows: successively carry out coarse crushing, medium crushing, passing the whole sample through a 40-mesh sieve (0.42 mm), checking visible gold on the sieve, mixing the sample under the sieve, reducing the sample, gradually finely crushing to a particle size less than 0.074 mm to obtain a chemical analysis sample, and then determining the gold content. However, due to the uneven distribution of native gold with a larger particle size in the sample in coarse-grained gold ore, the reproducibility of the gold content measured by the above processing and analysis method is poor; and because the probability of obtaining a sample containing native gold with a larger particle size is small, it will lead to a serious underestimation of the analysis result. Even if the number of sampling and analysis times is increased, it is difficult to obtain a correct analysis result, thus making it difficult to guide the gold ore exploration and evaluation work in a timely manner, and even underestimating the grade of the gold deposit. Summary of the Invention

[0004] The purpose of the invention is to overcome the deficiencies in the above prior art and provide a processing and analysis method for a coarse-grained gold ore sample. This method separates native gold with a larger particle size from the reduced sample through heavy sand separation, avoiding the difficulty of uniform dispersion of large-particle-size native gold, so as to improve the accuracy of gold content detection. Then, the heavy sand sample is directly subjected to wet digestion analysis to remove pretreatment processes such as roasting to reduce the risk of native gold loss during transfer. Finally, the gold content of the heavy sand sample and the gold content of the light mineral sample are weighted and averaged to obtain the gold content of the coarse-grained gold ore sample, solving the problem that it is difficult to accurately determine the gold content of coarse-grained gold ore in the prior art.

[0005] To achieve the above purpose, the technical solution adopted by the invention is: a processing and analysis method for a coarse-grained gold ore sample, characterized in that the method includes the following steps:

[0006] Step 1: Crush, screen, mix, and quarter the coarse-grained gold ore sample to obtain a quartered sample.

[0007] Step 2: Fine-crush and perform heavy mineral separation on the quartered sample obtained in Step 1 to obtain a heavy mineral sample and a light mineral sample.

[0008] Step 3: Perform wet digestion analysis on the heavy mineral sample obtained in Step 2 to obtain the gold content of the heavy mineral sample.

[0009] Step 4: Process the light mineral sample obtained in Step 2 and measure its gold content to obtain the gold content of the light mineral sample.

[0010] Step 5: Calculate the weighted average using the gold content of the heavy mineral sample obtained in Step 3 and the gold content of the light mineral sample obtained in Step 4 to obtain the gold content of the coarse-grained gold ore sample.

[0011] The above processing and analysis method for a coarse-grained gold ore sample is characterized in that after screening in Step 1, the coarse-grained gold ore sample with a particle size greater than 1 mm is crushed again until the particle size of all the coarse-grained gold ore samples in Step 1 is not greater than 1 mm; the minimum reliable weight for quartering is 1 kg.

[0012] The present invention controls the particle size of the coarse-grained gold ore sample to be not greater than 1 mm according to the particle size of native gold in the coarse-grained gold ore sample. This particle size is larger than the particle size of native gold in the coarse-grained gold ore sample, which can reduce the repeated crushing process of large-particle-size native gold; at the same time, reducing the particle size can lower the minimum reliable weight for quartering, effectively reducing the workload of subsequent sample processing. Referring to the Kjeldahl experience formula, the minimum reliable weight for quartering can be calculated as 1 kg, which is greatly reduced compared to the minimum reliable weight of 5 kg in the prior art.

[0013] The above processing and analysis method for a coarse-grained gold ore sample is characterized in that after fine-crushing in Step 2, the particle size of the quartered sample is not greater than 0.25 mm.

[0014] The present invention fine-crushes the quartered sample to make the particle size of the quartered sample not greater than 0.25 mm, which can fully dissociate native gold from associated minerals and improve the separation effect of heavy mineral separation; it can avoid the particle size of fine-crushing being too small, resulting in native gold being ground into thin flakes, increasing the specific surface area of native gold and reducing the specific gravity, which affects the effect of heavy mineral separation.

[0015] The above processing and analysis method for a coarse-grained gold ore sample is characterized in that in step two, the heavy sand separation is carried out by using a gravity separation device or manual panning. The process of the heavy sand separation is as follows: Put the quartered sample into the shaking table of the gravity separation device or the panning sand tray for manual panning, and wash it with a medium until the mass of the quartered sample remaining in the shaking table or the panning sand tray is not greater than 30 g, which is recorded as the heavy sand sample, and the remaining quartered sample washed out of the shaking table or the panning sand tray by the medium is the light mineral sample.

[0016] The present invention uses a medium for washing, which can remove light minerals with a smaller density and retain heavy minerals with a larger density containing native gold; by controlling the minimum reliable weight of the quartered sample, the representativeness of the quartered sample is ensured. At the same time, the mass of the heavy sand sample after heavy sand separation can be controlled to be not greater than 30 g, and the coarse-grained gold is controlled to remain in the heavy sand sample. All the heavy sand samples can be directly subjected to wet digestion analysis, reducing the risk of loss of native gold during the transfer of the heavy sand sample.

[0017] The above processing and analysis method for a coarse-grained gold ore sample is characterized in that the medium is water.

[0018] The above processing and analysis method for a coarse-grained gold ore sample is characterized in that the particle size of the processed light mineral sample in step four is not greater than 0.074 mm.

[0019] The above processing and analysis method for a coarse-grained gold ore sample is characterized in that the gold content w(Au) of the coarse-grained gold ore sample in step five is calculated by the following formula:

[0020] w(Au) = [M 1 × w(Au) A + M 2 × w(Au) B / (M 1 + M 2 ) ;

[0021] Among them, w(Au) is the gold content of the coarse-grained gold ore sample, with the unit of μg / g; M 1 is the mass of the heavy sand sample described in step two, with the unit of g; w(Au) A is the gold content in the heavy sand sample, with the unit of μg / g; M 2 is the mass of the light mineral sample, with the unit of g; w(Au) B is the gold content in the light mineral sample, with the unit of μg / g.

[0022] The present invention has the following advantages compared with the prior art:

[0023] 1. The present invention enriches and separates natural gold with larger particle size from the quartered sample by using heavy sand separation, avoiding the difficulty of uniform dispersion of large-particle natural gold during sample processing, and improving the precision of gold content detection in the sample. Then, the heavy sand sample is directly subjected to wet digestion analysis, eliminating the pretreatment processes such as roasting, which can reduce the risk of natural gold loss in the heavy sand sample during processes such as roasting, improve the accuracy of gold content determination in the heavy sand sample, and further improve the accuracy of gold content determination in the gold ore sample containing coarse gold particles.

[0024] 2. The present invention ensures the representativeness of the quartered sample by controlling the particle size of the sample and the minimum reliable weight of quartering in each process. Through heavy sand separation of the quartered sample, natural gold with high density and ductility is separated into the heavy sand sample, avoiding the difficulty of breaking large-particle natural gold during the processing of light mineral samples and affecting the precision of gold content detection in the gold ore sample containing coarse gold particles.

[0025] 3. The present invention can effectively reduce the minimum reliable weight of quartering and effectively reduce the workload of subsequent sample processing and the cost of processing and analysis of the gold ore sample containing coarse gold particles by reducing the particle size of the gold ore sample containing coarse gold particles after crushing.

[0026] The technical solution of the present invention will be further described in detail below through examples. Detailed implementation mode

[0027] Example 1

[0028] The gold ore sample containing coarse gold particles in this example is from Changgou Gold Mine, Hanyin, Shaanxi Province. The processing and analysis method includes the following steps:

[0029] Step 1: Crush and screen the gold ore sample containing coarse gold particles until the particle size of all the gold ore samples containing coarse gold particles is not greater than 1 mm, then mix and quarter them to obtain a quartered sample of 1012 g; retain the remaining mixed gold ore sample containing coarse gold particles, denoted as the sub-sample.

[0030] Step 2: Crush the quartered sample obtained in Step 1 to a particle size not greater than 0.25 mm, then place the quartered sample in a shaking table of a gravity separation device and wash it with water as the medium until the mass of the quartered sample remaining in the shaking table is not greater than 30 g. After drying, weigh it to obtain a heavy sand sample of 23.2 g and a light mineral sample of 986 g.

[0031] Step 3: Perform wet digestion analysis on the heavy sand sample obtained in Step 2 to obtain the gold content of the heavy sand sample as 85.9 μg / g.

[0032] Step 4: Process the light mineral sample obtained in Step 2 to a particle size not greater than 0.074 mm, then weigh 20 g of the light mineral sample for gold content determination to obtain the gold content of the light mineral sample as 0.68 μg / g.

[0033] Step 5. Calculate the gold content w(Au) of the coarse-grained gold ore sample by using the gold content of the heavy mineral sample obtained in Step 3 and the gold content of the light mineral sample obtained in Step 4:

[0034] w(Au) = (23.2 g × 85.9 μg / g + 986 g × 0.68 μg / g) / (23.2 g + 986 g)

[0035] = 2.64 μg / g.

[0036] Repeat the processing and analysis of the above sub-samples, including the following steps:

[0037] Step 1. Mix and reduce the sub-sample to obtain a reduced sample of 1010 g;

[0038] Step 2. Crush the reduced sample obtained in Step 1 to a particle size not greater than 0.25 mm, then put the reduced sample into a shaking table of a gravity separation device and wash it with water as the medium until the mass of the reduced sample remaining in the shaking table is not greater than 30 g. After drying, weigh it to obtain 18.7 g of heavy mineral sample and 985 g of light mineral sample;

[0039] Step 3. Conduct wet digestion analysis on the heavy mineral sample obtained in Step 2 to obtain a gold content of 112 μg / g for the heavy mineral sample;

[0040] Step 4. Process the light mineral sample obtained in Step 2 to a particle size not greater than 0.074 mm, then weigh 20 g of the light mineral sample for gold content determination to obtain a gold content of 0.48 μg / g for the light mineral sample;

[0041] Step 5. Calculate the gold content w(Au) of the coarse-grained gold ore sample by using the gold content of the heavy mineral sample obtained in Step 3 and the gold content of the light mineral sample obtained in Step 4:

[0042] w(Au) = (18.7 g × 112 μg / g + 985 g × 0.48 μg / g) / (18.7 g + 985 g)

[0043] = 2.56 μg / g.

[0044] The relative deviation RD% of the 2 repeated analyses = 100% × (2.64 - 2.56) / (2.64 + 2.56)

[0045] = 1.54%.

[0046] The above relative deviation is 1.54%, which is less than the allowable limit of the relative deviation of repeated analysis of precious metals required by the "Quality Management Specification for Geological and Mineral Laboratory Tests - Part 3: Chemical Composition Analysis of Rock and Mineral Samples" (DZ / T 0130.3), indicating that the processing and analysis method of Example 1 meets the control requirements of the precision of repeated analysis.

[0047] Comparative Example 1

[0048] The difference between this comparative example and Example 1 is that: in Step 1, the processed particle size of the sample before quartering is not greater than 2 mm, and the quartered sample obtained is 5 kg. The 5 kg quartered sample is continuously processed to a particle size not greater than 0.25 mm for heavy mineral separation; 22.6 g of heavy mineral sample and 4970 g of light mineral sample are obtained. The gold content in the heavy mineral sample is measured as 315 μg / g, and the gold content in the light mineral sample is 1.08 μg / g. Calculate the gold content w(Au) of the coarse-grained gold ore sample:

[0049] w(Au) = (22.6 g × 315 μg / g + 4970 g × 1.08 μg / g) / (22.6 g + 4970 g)

[0050] = 2.50 μg / g.

[0051] The measured gold content of the coarse-grained gold ore sample in this comparative example is 2.50 μg / g, which is in good agreement with the gold content of 2.60 μg / g measured in Example 1, indicating that the processing and analysis method of the coarse-grained gold ore sample in Example 1 can reduce the reliable weight of heavy mineral separation by reducing the particle size of the sample before quartering and reduce the workload.

[0052] Comparative Example 2

[0053] The difference between this comparative example and Example 1 is that: in Step 1, the processed particle size of the sample before quartering is not greater than 1 mm to obtain two quartered samples of 1 kg and 3 kg respectively; in Step 2, the two quartered samples obtained in Step 1 are respectively finely crushed to a particle size not greater than 0.149 mm, and then heavy mineral separation is carried out.

[0054] The gold content of the 1 kg reduced sample was measured to be 1.51 μg / g, and that of the 3 kg reduced sample was 2.67 μg / g. The test results of the two samples differed significantly. When the sampling amount of the reduced sample was 3 kg, the gold content was more consistent with the results of Comparative Example 1 and Example 1. However, increasing the sampling amount increased the workload of heavy mineral separation. At the same time, during the repeated tests, a high content value of 1.41 μg / g appeared in the gold content test value of the light mineral sample with a sampling amount of 3 kg. This was because the overly fine particle size caused some native gold to form thin flakes, increasing the specific surface area and affecting the effect of heavy mineral separation. Natural gold might have been mixed into the light mineral sample, indicating that overly fine particle size before heavy mineral separation would affect the accuracy of gold content testing for gold ore samples containing coarse gold particles.

[0055] Example 2

[0056] The gold ore sample containing coarse gold particles in this example is from Yangpingwan Gold Mine, Shiquan, Shaanxi Province. The processing and analysis method includes the following steps:

[0057] Step 1: Crush and screen the gold ore sample containing coarse gold particles until the particle size of all the gold ore sample containing coarse gold particles is not greater than 1 mm, then mix and reduce it to obtain a 1015 g reduced sample; retain the remaining mixed gold ore sample containing coarse gold particles, denoted as the sub-sample.

[0058] Step 2: Grind the reduced sample obtained in Step 1 to a particle size not greater than 0.25 mm, then place the reduced sample in a pan for manual panning and wash it with water as the medium until the mass of the reduced sample remaining in the pan is not greater than 30 g. After drying, weigh it to obtain a 10.9 g heavy mineral sample and a 989 g light mineral sample.

[0059] Step 3: Perform wet digestion analysis on the heavy mineral sample obtained in Step 2 to obtain a gold content of 451 μg / g for the heavy mineral sample.

[0060] Step 4: Process the light mineral sample obtained in Step 2 to a particle size not greater than 0.074 mm, then weigh 20 g of the sample for gold content determination to obtain a gold content of 0.45 μg / g for the light mineral sample.

[0061] Step 5: Use the gold content of the heavy mineral sample obtained in Step 3 and the gold content of the light mineral sample obtained in Step 4 to calculate the gold content w(Au) of the gold ore sample containing coarse gold particles:

[0062] w(Au) = (10.9 g × 451 μg / g + 989 g × 0.45 μg / g) / (10.9 g + 989 g)

[0063] = 5.36 μg / g.

[0064] The above-mentioned sub-samples are repeatedly processed and analyzed, including the following steps:

[0065] Step 1: Mix and quarter the sub-samples to obtain a quartered sample of 1005 g; retain the remaining mixed sub-samples.

[0066] Step 2: Crush the quartered sample obtained in Step 1 to a particle size not greater than 0.25 mm, then place the quartered sample in a panning tray for manual panning with water as the medium until the mass of the quartered sample remaining in the panning tray is not greater than 30 g. After drying, weigh it to obtain a heavy mineral sample of 14.6 g and a light mineral sample of 987 g.

[0067] Step 3: Conduct wet digestion analysis on the heavy mineral sample obtained in Step 2 to obtain a gold content of 316 μg / g in the heavy mineral sample.

[0068] Step 4: Process the light mineral sample obtained in Step 2 to a particle size not greater than 0.074 mm, then weigh 20 g of the sample for gold content determination to obtain a gold content of 0.94 μg / g in the light mineral sample.

[0069] Step 5: Use the gold content of the heavy mineral sample obtained in Step 3 and the gold content of the light mineral sample obtained in Step 4 to calculate the gold content w(Au) of the coarse-grained gold ore sample:

[0070] w(Au) = (14.6 g × 316 μg / g + 987 g × 0.96 μg / g) / (14.6 g + 987 g)

[0071] = 5.55 μg / g

[0072] The relative deviation RD% of 2 repeated analyses = 100% × (5.55 - 5.36) / (5.55 + 5.36)

[0073] = 1.74%.

[0074] The above relative deviation is 1.74%, which is less than the allowable limit of the relative deviation of repeated analysis of precious metals required in "Quality Management Specification for Geological and Mineral Laboratory Testing - Part 3: Chemical Analysis of Rock and Mineral Samples" (DZ / T 0130.3), indicating that the processing and analysis method of Example 2 meets the control requirements of the precision of repeated analysis.

[0075] Comparative Example 3

[0076] The processing and analysis method of this comparative example includes the following steps:

[0077] Step 1: Mix and quarter the remaining mixed sub-samples retained in Step 1 of Example 2 to obtain a quartered sample of 1008 g.

[0078] Step 2: All the reduced samples obtained in Step 1 are processed to a particle size not greater than 0.25 mm, then mixed and reduced to obtain 200 g of reduced samples. Then all are processed to a particle size not greater than 0.074 mm, and 4 samples of 20 g each are weighed for repeated analysis of the gold content. The results are 1.65 μg / g, 3.70 μg / g, 7.00 μg / g, and 3.26 μg / g respectively. The average value of the 4 analysis results is 3.90 μg / g, and the standard deviation is 57.5%.

[0079] The processing and analysis method of this comparative example does not adopt heavy sand separation analysis, and the obtained results have poor precision, and the average value is lower than the detection result of Example 2, so it is impossible to correctly evaluate the gold grade of the coarse-grained gold ore sample.

[0080] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A processing and analysis method for a coarse-grained gold ore sample, characterized in that: The method comprises the following steps: Step 1: crushing, screening, mixing and reducing the coarse-grained gold ore sample to obtain a reduced sample; Step 2: crush the reduced sample obtained in step 1 and separate the heavy sand to obtain a heavy sand sample and a light mineral sample; Step 3: Perform wet digestion analysis on the heavy sand sample obtained in step 2 to obtain the gold content of the heavy sand sample; Step 4: Process the light mineral sample obtained in step 2 and determine the gold content to obtain the gold content of the light mineral sample; Step 5: Calculate the weighted average using the gold content of the heavy sand sample obtained in step 3 and the gold content of the light mineral sample obtained in step 4 to obtain the gold content of the coarse-grained gold ore sample.

2. The processing and analysis method of a coarse-grained gold ore sample according to claim 1, characterized in that: After the screening in step one, the coarse gold ore samples with a particle size greater than 1 mm are crushed again until the particle size of all coarse gold ore samples in step one is no greater than 1 mm; the minimum reliable weight of the reduction is 1 kg.

3. The processing and analysis method of a coarse-grained gold ore sample according to claim 1, characterized in that: The particle size of the sample after fine crushing and reduction in step 2 is not greater than 0.25 mm.

4. The processing and analysis method of a coarse-grained gold ore sample according to claim 1, characterized in that: The heavy sand separation described in step 2 is carried out using gravity sorting equipment or manual washing. The process of heavy sand separation is: put the reduced sample into the shaking table of the gravity sorting equipment or the manual washing pan, and use the medium to wash it until the mass of the reduced sample remaining in the shaking table or the pan is no more than 30g, which is recorded as the heavy sand sample, and the rest of the reduced sample washed out of the shaking table or the pan by the medium is the light mineral sample.

5. The method for processing and analyzing a coarse-grained gold ore sample according to claim 4, characterized in that: The medium is water.

6. The method for processing and analyzing a coarse-grained gold ore sample according to claim 1, characterized in that: The particle size of the light mineral sample after processing in step 4 is no more than 0.074 mm.

7. The method for processing and analyzing a coarse-grained gold ore sample according to claim 1, characterized in that: The gold content w (Au) of the coarse-grained gold ore sample in step 5 is calculated by the following formula: w(Au)=[M1×w(Au) A +M2×w(I) B ] / (M1+M2); Wherein, w(Au) is the gold content of the coarse-grained gold ore sample, in μg / g; M1 is the mass of the heavy sand sample described in step 2, in g; w(Au) A is the gold content of the heavy sand sample, in μg / g; M2 is the mass of the light mineral sample, in g; w(Au) B It is the gold content of light mineral samples, in μg / g.