WO2024045687A2 - Method for pre-selection and discarding and reducing over-grinding of gold ores - Google Patents

Abstract

A method for pre-selection and discarding and reducing over-grinding of gold ores. Firstly, settled sand of a cyclone in a gold ore grinding and classification closed-loop circulation system is sieved and classified to obtain a coarse-grained ore, an intermediate-grained mineral and a fine-grained mineral; the coarse-grained mineral is then returned to a ball mill for regrinding, the intermediate-grained mineral is introduced into a dense-medium sorting system, so as to obtain a dense-medium sorted tailing, which is treated as waste rock, and a dense-medium sorted concentrate, which is returned to the ball mill for regrinding; and finally, the fine-grained mineral is subjected to flash flotation, so as to obtain a high-grade gold concentrate as a product, and a flash flotation tailing, which is returned to the ball mill for regrinding. The method can achieve efficient separation between a main useful mineral and a gangue mineral in a gold mine, and significantly reduce the amount of ores entering the flotation process; and useful minerals dissociated by a monomer in an ore grinding and classification closed loop can further be floated in advance, which prevents this portion of minerals from being continuously circulated and accumulated during a cyclone classification process due to large specific gravity, and prevents the Au recovery rate from being affected by over-grinding.

Description

A method for pre-selecting, discarding and reducing over-grinding of gold mines Technical field

The invention relates to a method for pre-selecting gold mines, discarding waste and reducing over-grinding, and belongs to the technical field of mineral processing.

Background technique

In the grinding and classification circuit, the ore is over-grinded to varying degrees. For those ores with high density, brittleness and brittleness, the degree of over-grinding is even more serious. Over-grinding not only causes a large amount of valuable heavy metals to be lost, but also reduces the production capacity of the grinding machine and increases energy consumption. Over-grinding directly affects the economic benefits of the mineral processing plant. In addition, the sludge phenomenon caused by over-grinding also causes great difficulties in subsequent operations such as sorting and dehydration. Hydraulic classification has fundamental flaws that cannot be overcome by improving equipment parameters and process flow. Therefore, currently adopted measures to improve classification efficiency include the introduction of screening operations, secondary classification, Huji cone hydraulic classifier, Huji Basic screens, etc., play a very limited role in solving the problem of over-grinding of valuable heavy minerals.

The development of gold resources and the generation of large amounts of tailings restrict the development of mining enterprises. Therefore, from the perspective of green and energy-saving mine construction, it has certain practical significance to use heavy media mineral processing technology for pre-selection and tailing. Coarse-grained waste rock can be used as underground refill aggregate or building material aggregate to reduce the amount of tailings and extend the service life of the tailings reservoir. At present, my country's heavy media pre-selection and sorting technology is not widely used in industrial applications in non-ferrous metal sorting. This technology has many application examples in foreign countries in the separation of copper, lead, zinc, tungsten and other metal ores. Because the main elements of gold mineral resources are calculated in g/t, and the content is much lower than that of other metal ores, it is difficult to use heavy media separation.

The invention patent application with publication number CN113634346A involves a method for pre-selecting and discarding non-ferrous metal ores. Its main technical means are: (1) crushing the non-ferrous metal ore raw ore and then performing the first screening and classification to obtain the first coarse ore and the first Fine ore and the first qualified ore; (2) carry out intelligent ore sorting on the first coarse ore to obtain the first coarse concentrate and gangue tailings; (3) crush the first coarse concentrate and carry out the third Second screening and classification, the second fine ore and the second qualified ore are obtained; (4) The first fine ore and the second fine ore are subjected to heavy media beneficiation to obtain concentrate and gangue tailings; the concentrate is qualified mine.

The main shortcomings of the above-mentioned patented technology are: this patent is suitable for non-ferrous metal ore raw ore, and the raw ore crushing particle size is relatively coarse. In the implementation process of gold mines, the main element of gold ore resources is gold, and the content is in g/t, and the degree of dissociation is It is not enough to achieve the heavy medium separation effect; this patent combines the particularity of gold resources with the applicability of heavy medium separation, uses cyclone sand settling as the raw material for separation, and relies on process mineralogy analysis to fully resolve the problem. The separated useful minerals and gangue minerals are separated to obtain heavy media separation tailings with a lower gold grade than the flotation tailings.

technical problem

The technical problem to be solved by this invention is to make full use of the close relationship between pyrite and gold minerals, the difference in specific gravity between pyrite and gangue minerals, the easy-to-float property of pyrite, etc., to provide a method with good separation effect. , has strong adaptability to gold mines and can also solve the over-grinding problem of the grinding and grading system.

Technical solutions

In order to solve this technical problem, the present invention adopts the following technical solutions:

A method for pre-selecting, discarding and reducing over-grinding of gold mines, which is characterized by including the following steps:

(1) Screen and classify the cyclone sand in the gold ore grinding and classification closed-circuit system to obtain coarse-grained minerals, intermediate-grained minerals and fine-grained minerals; the particle size of the coarse-grained minerals is ≥3mm , the fine-grained minerals are ≤0.5mm;

(2) Return the coarse-grained minerals to the ball mill for regrinding;

(3) Enter the intermediate-grade minerals into the heavy media separation system, obtain the heavy medium separation tailings and treat them as waste rock, and obtain the heavy medium separation concentrate and return it to the ball mill for regrinding;

(4) The fine-grained minerals are subjected to flash flotation to obtain high-grade gold concentrate as the product, and the flash flotation tailings are obtained and returned to the ball mill for re-grinding.

Preferably, the particle size of the coarse-grained mineral is ≥5 mm.

Preferably, the fine-grained minerals are ≤0.25mm.

Preferably, the intermediate-grade minerals enter the heavy medium separation system, and the heavy medium separation tailings are treated as waste rock. The waste disposal yield is determined according to the Au grade of the tailings, and the Au grade of the tailings is ≤ 0.15g/t. More preferably ≤0.1g/t, the waste rock is used as construction sand and filling material; the heavy medium separation concentrate is obtained and returned to the ball mill for re-grinding.

Further preferably, the Au grade of the tailings is ≤0.1g/t.

Preferably, the heavy medium separation system includes heavy medium liquid preparation, screening and demediation, and magnetic separation and washing.

Preferably, the heavy medium used for separating the heavy medium is ferrosilicon powder.

Preferably, the fine-grained minerals are subjected to flash flotation to obtain high-grade gold concentrate as the product, with a gold grade of ≥ 60 g/t, and the flash flotation tailings are obtained and returned to the ball mill for re-grinding.

Preferably, the gold ore is a quartz vein type gold ore.

beneficial effects

Compared with the existing technology, the positive effects of the present invention are as follows:

The present invention performs particle size classification by classifying the cyclone sand in the closed-circuit grinding and classification system, and by means of a combination of closed-circuit screening, heavy medium separation, and flash flotation, the treatment process of ores of different particle sizes is reasonably designed to achieve coarse The particle size cyclone grit is returned to grinding, the intermediate particle size cyclone grit is discarded and pre-enriched, and the fine-grained product is flash flotated to obtain high-grade gold concentrate. The method provided by the invention can not only realize efficient separation between main useful minerals and gangue minerals in gold mines, significantly reduce the amount of ore entering the flotation process, and save costs; it can also pre-flotate the monomer solution in the closed circuit of grinding and classification. Isolated useful minerals can avoid the continuous accumulation of these minerals in the cyclone classification process due to their specific gravity, causing over-grinding and affecting the Au recovery rate. This will provide technical support for improving the economic benefits of gold mines, green and efficient development of mines, and resource utilization. .

Compared with the aforementioned invention patent application with publication number CN113634346A, which involves a method of pre-selecting and discarding non-ferrous metal ores, this invention has the following technical advantages: it is better suited for pre-selecting and discarding of gold ore resources, and the gold grade obtained is lower than that of flotation tailings gold. The high-grade waste tailings have a higher waste yield; and this patent applies pre-waste removal and over-grinding suppression to the same raw material, which is easy to implement and widely used.

Description of drawings

Figure 1 is a process flow diagram of an embodiment of the present invention.

Figure 2 is a graph of the tailings productivity and distribution rate under different density conditions of (-5mm+0.28mm) sample heavy media separation in the embodiment of the present invention.

Figure 3 is a graph of the tailings productivity and distribution rate under different density conditions of (-2mm+0.28mm) sample heavy media separation in the embodiment of the present invention.

Embodiments of the invention

In order to better understand and implement the present invention, the present invention will be further described below in conjunction with specific embodiments.

The method of the present invention includes a series of process steps that can be implemented in equipment meeting the required process conditions. As shown in Figure 1, after the raw ore is ground, the product is pumped to the cyclone for classification. The cyclone overflow enters the main flotation operation. After the cyclone sand is screened by a double-layer vibrating screen, coarse-grained minerals and intermediate particles are obtained. grade minerals and fine-grained minerals.

Coarse grade minerals return to the ball mill;

Fine-grained minerals enter the flash flotation system, the flash flotation concentrate is sold as a product, and the flash flotation tailings are returned to the ball mill;

The intermediate grade minerals enter the heavy medium separation system. The heavy medium (ferrosilicon powder) and the intermediate grade minerals are mixed in the heavy medium mixing barrel and pumped into the heavy medium cyclone. The heavy medium separation concentrate is discharged from the cyclone. The underflow is discharged and screened and deinterposed by a linear vibrating screen. The products on the screen are cleaned by a cleaning screen and then fed into the ball mill. The sorted tailings are discharged from the cyclone overflow and screened by a linear vibrating screen. After deintermediation, the products on the screen are cleaned by a cleaning screen. Then thrown out as final tailings. The products screened by the two de-medium vibrating screens are dehydrated and returned to the heavy medium mixing barrel, and the water is recycled.

Example 1

Application situation of flash flotation of fine-grained products with cyclone sand settling: The fine-grained product (≤0.25mm) with cyclone sand settling in a gold mine concentrates at a flotation concentration of 60% and a flotation time of 1 minute. The grade is 77.23g/t, the yield is 2.45%, the Au recovery rate is 44.18%, the recovery rate of pyrite monomer and other metal sulfide symbionts is 95.43%, and the recovery rate of Fulian biomass is 80.61%, which has reached the predetermined level. The purpose of flotation monomer is to dissociate useful minerals, which can effectively suppress the over-grinding problem.

Example 2

Sorting conditions of heavy medium with sand settling in a mine's cyclone:

Cyclone sand settling (-5mm+0.28mm) and (-2mm+0.28mm) samples were prepared respectively, and the heavy medium cyclone mineral processing test was carried out. The test data are shown in Table 1.

Draw the tailings yield and distribution rate curves of the (-5mm+0.28mm) sample heavy medium separation under different density conditions based on the heavy medium mineral processing test results, and (-2mm+0.28mm) the tailings production rate of the sample heavy medium separation under different density conditions. , the distribution rate curve is shown in Figure 2 and Figure 3.

The heavy media sorting results show:

(1) As the density of heavy media continues to increase, the tailings yield continues to increase, and the distribution rate of Au and S in the concentrate shows a downward trend.

(2) Comparing the Au grade in the tailings, the sorting effect of the 2mm+0.28mm sample is slightly better than that of -5mm+0.28mm.

(3) When the separation density of the -2mm+0.28mm sample is 1.92g/m³, the tailings yield is 47.69%. The Au and S grades in the tailings are 0.17g/t and 0.1% respectively. The Au in the concentrate , S distribution rates are 94.14% and 93.58% respectively.

Example 3

The cyclone sand flash flotation + heavy medium separation situation in a mine: The cyclone sand was screened through 5mm and 0.25mm vibrating screens respectively to obtain coarse-grained minerals (>5mm) and intermediate-grained minerals. (0.25-5mm) and fine-grained minerals (>0.25mm). The separation medium used is a heavy medium liquid prepared from ferrosilicon powder and water. The results of the heavy media separation test on coarse-grained and intermediate-grained minerals are shown in Table 2.

The test results show that: due to insufficient monomer dissociation of coarse-grained minerals, the Au grade of the tailings fluctuates greatly, and a stable tailing product cannot be obtained, so this product needs to be returned to the ball mill for re-grinding; the intermediate-grained grade products are evenly distributed in each particle range. It can obtain better tailing products and lower tailing Au grade (≤0.15g/t, lower than the Au grade of flotation tailings).

Fine-grained products (<0.25mm) were subjected to flash flotation. The test results are shown in Table 3.

The results of the flotation concentration test show that as the flotation concentration increases, the Au grade and Au recovery rate of the concentrate first increase and then decrease; when the flotation concentration is 55%, the recovery rate is the highest, and when the flotation concentration is 55%, the recovery rate is the highest. At 60%, the concentrate grade is the highest (77.95g/t).

Claims (9)

1. A method for pre-selecting, discarding and reducing over-grinding of gold mines, which is characterized by including the following steps:

   (1) Screen and classify the cyclone sand in the gold ore grinding and classification closed-circuit system to obtain coarse-grained minerals, intermediate-grained minerals and fine-grained minerals; the particle size of the coarse-grained minerals is ≥3mm , the fine-grained minerals are ≤0.5mm;

   (2) Return the coarse-grained minerals to the ball mill for regrinding;

   (3) Enter the intermediate-grade minerals into the heavy media separation system, obtain the heavy medium separation tailings and treat them as waste rock, and obtain the heavy medium separation concentrate and return it to the ball mill for regrinding;

   (4) The fine-grained minerals are subjected to flash flotation to obtain high-grade gold concentrate as the product, and the flash flotation tailings are obtained and returned to the ball mill for re-grinding.
2. The method for pre-selecting gold mines, discarding waste and reducing over-grinding according to claim 1, characterized in that: the particle size of the coarse-grained minerals is ≥5 mm.
3. The method for pre-selecting gold mines, discarding waste and reducing over-grinding according to claim 1, characterized in that: the fine-grained minerals are ≤0.25mm.
4. The method for pre-selecting, discarding and reducing over-grinding of gold mines according to claim 1, 2 or 3, characterized in that: the intermediate size minerals enter the heavy media separation system, and the heavy medium separation tailings are obtained as waste. Stone treatment, determine the waste discarding yield according to the Au grade of the tailings, the Au grade of the tailings is ≤0.15g/t, more preferably ≤0.1g/t, and the waste rock is used as construction sand and filling material; heavy media separation is obtained The concentrate is returned to the ball mill for further grinding.
5. The method for pre-selecting gold mines, discarding waste and reducing over-grinding according to claim 4, characterized in that: the Au grade of the tailings is ≤0.1g/t.
6. The method for pre-selecting gold mines, discarding waste and reducing over-grinding according to claim 1, characterized in that the heavy medium separation system includes heavy medium liquid preparation, screening and media removal and magnetic separation and washing.
7. The method for pre-selecting gold mines, discarding waste and reducing over-grinding according to claim 6, characterized in that: the heavy medium used for sorting the heavy medium is ferrosilicon powder.
8. The method for pre-selecting gold mines, discarding waste and reducing over-grinding according to claim 1, characterized in that: the fine-grained minerals are flash flotated to obtain high-grade gold concentrate as a product, with a gold grade of ≥ 60g/t , the flash flotation tailings are obtained and returned to the ball mill for further grinding.
9. The method for pre-selecting, discarding and reducing over-grinding of gold ore according to claim 1, characterized in that: the gold ore is a quartz vein type gold ore.