A method for simultaneously recovering native copper and quartz from native copper ore

Abstract

The application discloses a method for simultaneously recovering native copper and quartz from native copper ore, and belongs to the technical field of mineral processing. The method is based on the density difference between native copper and quartz, and adopts a process flow of'stage grinding-classification-recovery of native copper by gravity separation-recovery of fine native copper by flotation-tailings combined purification of quartz'. Specifically, after crushing and grinding, the native copper is recovered by adopting spiral chute roughing and table concentration after classification by a hydrocyclone, and the fine native copper is recovered by flotation; the tailings of gravity separation and the tailings of flotation are combined, and then iron is removed by magnetic separation, silicate impurities such as mica feldspar are removed by reverse flotation, and high-grade quartz concentrate is obtained by acid leaching purification if necessary. The application realizes the simultaneous and efficient recovery of native copper and quartz, the grade of copper concentrate is greater than or equal to 35%, the copper recovery rate is greater than or equal to 82%, the grade of quartz concentrate SiO2 is greater than or equal to 98.5%, the tailings discharge is reduced by more than 60%, and the resource utilization rate and economic benefit are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and specifically to a mineral processing method for simultaneously recovering native copper and quartz from native copper ore. Background Technology

[0002] Native copper ore refers to minerals where copper is primarily found in elemental form (Cu). 0 The copper deposits in this area contain native copper minerals that are mostly granular, platy, or dendritic, embedded in quartz veins, silicified host rocks, or volcanic rocks. The density of native copper is 8.89 g / cm³, while that of quartz is 2.65 g / cm³. The density ratio of the two in aqueous medium is approximately 4.8, indicating a significant density difference that provides a good physical basis for gravity separation.

[0003] Native copper deposits are distributed in some regions of my country (such as northwestern Sichuan, the middle and lower reaches of the Yangtze River, and central Yunnan). The ore typically contains 55%–80% quartz and 0.3%–2.0% native copper, with small amounts of iron minerals, mica, feldspar, and other impurities. Traditional native copper ore beneficiation processes focus solely on recovering copper metal, generally employing a "gravity separation pre-enrichment—flotation purification" process or a single flotation process, with gangue minerals (mainly quartz) directly discharged as tailings. This process suffers from the following prominent problems: (1) Serious waste of quartz resources. Quartz accounts for 55% to 80% of natural copper ore, and vein quartz has high purity. After purification, it can be used as a high-quality silicon raw material for industries such as glass, ceramics, casting, and photovoltaics. Traditional processes discharge all of it into tailings ponds, resulting in huge waste of resources. (2) Tailings ponds face high pressure and environmental risks. Large amounts of tailings not only occupy land resources, but also pose environmental safety hazards such as dam failure and heavy metal leakage. The construction and operation and maintenance costs of tailings ponds are also high. (3) Low recovery efficiency of fine-grained native copper. Native copper has good ductility and is prone to producing flaky and flake-like fine-grained copper during grinding. Traditional gravity separation equipment has poor recovery effect on native copper with a particle size of -74μm, resulting in copper metal loss. (4) The quartz purification process is not targeted enough. Existing quartz sand purification processes are mostly developed for raw materials such as vein quartz and quartzite. For natural copper ore gravity separation tailings, a special raw material (containing a small amount of natural copper, iron minerals and silicate impurities), there is a lack of systematic joint purification processes.

[0004] With the continuous advancement of comprehensive utilization of tailings in China and the rapid growth in market demand for high-purity quartz sand, developing a mineral processing method that can simultaneously and efficiently recover natural copper and quartz from natural copper mines is of great significance for improving resource utilization, reducing tailings emissions, and enhancing the economic benefits of mines. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned shortcomings in the existing technology and provide a method for simultaneously recovering native copper and quartz from native copper ore. This method uses gravity separation as the core to recover native copper, flotation to supplement the recovery of fine-grained native copper, and a combined magnetic separation-reverse flotation (-acid leaching) process to purify quartz, thereby achieving the simultaneous and efficient recovery of both copper and silicon resources.

[0006] To achieve the above objectives, the technical solution of the present invention includes the following steps: (1) Crushing and grinding: After coarse crushing by a jaw crusher and medium crushing by a double roll crusher, the raw copper ore is fed into a ball mill for wet grinding. The grinding fineness is controlled so that the content of -200 mesh (74μm) is 55% to 70%, so that the raw copper particles are fully liberated from the quartz gangue, while avoiding over-grinding that causes the raw copper particles to elongate and deform. A staged grinding process is preferred. After the first stage of grinding to 35% to 50% of the raw copper is ground, it is classified by a hydrocyclone. The underflow is returned to the ball mill for re-grinding, and the overflow is used for subsequent classification operations. (2) Hydrocyclone Classification: The grinding slurry is fed into a hydrocyclone for classification, with a classification particle size of 50–74 μm (preferably 60 μm). The underflow (coarse particles, +50–74 μm) enters the gravity separation process, and the overflow (fine particles, -50–74 μm) enters the fine-particle natural copper flotation process. The classification process can achieve "separation and separate processing of coarse and fine particles", avoiding interference from fine particles on the gravity separation effect. (3) Gravity separation roughing in spiral sluice: The underflow from the hydrocyclone is fed into the spiral sluice for gravity separation. The spiral sluice utilizes the combined effects of gravity, centrifugal force, and inclined film flow to cause denser natural copper particles to move outwards and concentrate, while less dense quartz particles move inwards. The feed concentration is controlled at 20%–30% (preferably 22%–28%), and the separation parameters are optimized by adjusting the flushing water volume. The spiral sluice can separate particles ranging from 0.02 to 0.3 mm, with a large throughput, no power required, and low water consumption. Gravity concentrate (enriched natural copper), gravity medium, and gravity tailings (enriched quartz) are obtained. The gravity concentrate is then fed into a shaking table for further cleaning, the gravity medium is returned to the spiral sluice for re-selection, and the gravity tailings are sent to the quartz purification process. (4) Shaking Table Concentration: The gravity concentrate from the spiral sluice is fed into the shaking table for concentration. The shaking table separates minerals based on density differences and differential movement characteristics of the bed surface, resulting in clear zoning and high concentration efficiency. The operating parameters are: stroke 4-8 mm, stroke rate 250-320 times / min, bed surface inclination angle 3°-5°, and flushing water volume 0.8-1.5 L / (s·m²). Copper concentrate, shaking table middlings, and shaking table tailings are obtained. The shaking table middlings are returned to the spiral sluice to form a closed-loop cycle, and the shaking table tailings are used for quartz purification. (5) Fine-grained native copper flotation: The hydrocyclone overflow (fine-grained grade) is adjusted to a mass concentration of 30%–35% before flotation to recover fine-grained, flaky native copper. The reagent system is as follows: lime is used as a pH adjuster to control the pulp pH to 8.0–9.5; butyl xanthate or isoamyl xanthate is used as a collector at a dosage of 60–150 g / t; No. 2 oil is used as a frother at a dosage of 15–40 g / t. The flotation process consists of one roughing, one to two scavenging, and one to two cleaning stages. The flotation concentrate is a fine-grained copper concentrate, which is combined with the shaking table copper concentrate to form the final copper concentrate product; the flotation tailings are sent to quartz purification operations. (6) Quartz purification: The gravity separation tailings, shaking table tailings and flotation tailings (quartz mass fraction of about 80% to 92%) are combined and purified by magnetic separation to remove iron and reverse flotation in sequence: ① Magnetic separation for iron removal: A combined process of weak magnetic separation and strong magnetic separation is adopted. First, weak magnetic separation with a magnetic field strength of 1000-2000 Oe is used to remove strongly magnetic minerals such as magnetite. Then, wet strong magnetic separation with a magnetic field strength of 8000-14000 Oe (preferably 10000-12000 Oe) is used to remove weakly magnetic minerals such as hematite, limonite, ilmenite and iron-containing silicates. ② Reverse flotation purification: The magnetic concentrate is slurry adjusted to a mass concentration of 30%–35%, and the pH is controlled to 9.0–11.0 with sodium hydroxide or sodium carbonate. Starch is used as a quartz depressant at a dosage of 150–400 g / t; sodium oleate or dodecylamine is used as a collector for mica and feldspar silicate impurities at a dosage of 40–120 g / t. The reverse flotation process consists of one roughing stage and one to two cleaning stages. The froth product is tailings containing mica and feldspar impurities, while the product in the tank is quartz concentrate. Reverse flotation utilizes the difference in surface electrical properties between impurity minerals such as mica and feldspar and quartz to selectively float away impurities, leaving the quartz in the tank. It has the advantages of low reagent dosage and high cleaning efficiency. ③ Optional acid leaching purification: When higher purity of quartz concentrate is required (such as photovoltaic grade and electronic grade quartz), the reverse flotation quartz concentrate is leached with a 5% to 15% hydrochloric acid or sulfuric acid solution at 60 to 90°C for 1 to 3 hours, with a solid-liquid ratio of 1:2 to 1:4. After leaching, the concentrate is filtered and washed until neutral to further remove impurities such as iron, aluminum, and calcium, and obtain high-purity quartz concentrate with a SiO2 grade ≥99.5%. (7) Dehydration and drying: The copper concentrate and quartz concentrate are concentrated by a thickener, filtered by a filter press or vacuum filter, and dried by a drying kiln or fluidized bed dryer, respectively, and then inspected, packaged and stored. The drying temperature of the copper concentrate is controlled at 80-120℃, and the drying temperature of the quartz concentrate is controlled at 100-150℃.

[0007] The beneficial effects of this invention are as follows: (1) Simultaneous recovery and high resource utilization rate. While recovering natural copper, this invention purifies quartz, which accounts for 55% to 80% of the total ore, into qualified siliceous raw materials, achieving "two harvests from one mine". The tailings discharge is reduced by more than 60%, which significantly reduces the pressure on tailings ponds and environmental risks. (2) Coarse and fine grade separation and separate processing. The grinding product is divided into coarse and fine grades by hydrocyclone. The coarse grade is recovered by gravity separation (making full use of density difference), and the fine grade is recovered by flotation (solving the problem of low gravity separation efficiency of fine-grained natural copper). This achieves efficient recovery of natural copper of all grades, with a total copper recovery rate of ≥82%. (3) Gravity separation is the main process and the cost is low. The spiral chute roughing-shaking table cleaning process is used as the core process for the recovery of coarse natural copper. The equipment has a large processing capacity, requires no power, consumes little water, has low operating costs, and the copper concentrate grade is ≥35%. (4) Combined purification, superior quartz quality. The combined process of "magnetic separation to remove iron - reverse flotation to remove silicate impurities - (acid leaching for deep purification)" is adopted to address the characteristics of natural copper ore tailings. It can stably obtain high-quality quartz concentrate with SiO2 grade ≥98.5% and Fe2O3 ≤0.05%, which meets the sand requirements of industries such as glass, ceramics, and casting. After acid leaching, the purity can reach over 99.5%, meeting the needs of the high-end market. (5) Closed-loop process and environmentally friendly reagents. The middlings are returned for reprocessing to form a closed-loop cycle, resulting in less metal loss; reverse flotation removes only a small amount of impurities, requiring less reagents; copper flotation uses conventional xanthate reagents, which are environmentally friendly. Attached Figure Description

[0008] Figure 1 This is a process flow diagram of a method for simultaneously recovering native copper and quartz from native copper ore according to the present invention. Detailed Implementation

[0009] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0010] Example 1

[0011] A certain quartz vein-type native copper deposit has the following main chemical composition: SiO2 68.5%, Cu 0.76%, TFe 0.52%, Al2O3 5.2%, CaO 1.2%, MgO 0.6%, K2O 1.8%, Na2O 0.9%, and loss on ignition 0.52%. The copper in the ore mainly exists as elemental native copper, with a grain size of 0.03–0.4 mm. The gangue minerals are mainly quartz, containing small amounts of mica, feldspar, and iron minerals.

[0012] The specific steps and parameters of the process according to this invention are as follows: (1) Crushing and grinding: The raw ore is coarsely crushed to -100mm by a jaw crusher and medium crushed to -15mm by a double roll crusher before being fed into a ball mill for wet grinding. A single-stage closed-circuit grinding is adopted, and the grinding fineness is controlled to -200 mesh, accounting for 62%. (2) Hydrocyclone classification: The grinding slurry is classified by a hydrocyclone with a classification particle size of 60 μm. The underflow (+60 μm, yield about 38%) enters the spiral sluice for gravity separation, and the overflow (-60 μm, yield about 62%) enters the fine-grained natural copper flotation. (3) Gravity separation roughing in spiral sluice: After the slurry underflow of the hydrocyclone is adjusted to a concentration of 25%, it is fed into the spiral sluice (diameter 600mm, 3 heads) to obtain a gravity concentrate yield of 4.2% and a Cu grade of 12.8%, and a gravity tailings (quartz enrichment) yield of 33.8%. The gravity concentrate is then fed into the shaking table for further cleaning, and the middlings are returned to the spiral sluice. (4) Shaking table refining: The concentrate is fed into the shaking table via a spiral chute with a stroke of 6 mm, a stroke rate of 290 times / min, a table inclination angle of 4°, and a flushing water volume of 1.0 L / (s·m²). The yield of copper concentrate is 1.6%, the Cu grade is 38.5%, and the tailings yield of the shaking table is 2.6%, which is then used for quartz purification. (5) Fine-grained native copper flotation: The hydrocyclone overflow slurry was adjusted to a concentration of 32%, and lime was added to adjust the pH to 8.5. The dosage of butyl xanthate was 90 g / t, and the dosage of No. 2 oil was 25 g / t. One roughing, one scavenging, and one cleaning were performed. The yield of fine-grained copper concentrate was 0.52%, the Cu grade was 32.6%, and the flotation tailings yield was 61.48%, which was then used for quartz purification. (6) Quartz purification: The gravity separation tailings, shaking table tailings, and flotation tailings are combined (total yield 97.88%, SiO2 approximately 70.1%), and then processed sequentially as follows: ① Weak magnetic separation (1500 Oe) removes strong magnetic iron, strong magnetic separation (11000 Oe) removes weak magnetic iron; ② Reverse flotation: Adjust pH to 10.0 with NaOH, use 250g / t of starch and 80g / t of sodium oleate, performing one roughing and one cleaning process. The product in the tank is quartz concentrate. (7) Dehydration and drying: Copper concentrate (shaking table copper concentrate + fine-grained copper concentrate combined) and quartz concentrate are concentrated, filtered and dried (105℃) to obtain the final product.

[0013] Final product specifications: Copper concentrate: Cu grade 36.8%, copper recovery rate 84.2%; Quartz concentrate: SiO2 98.7%, TFe 0.038%, Al2O3 0.42%, CaO 0.08%, yield 62.5% (of the original ore), quartz recovery rate 90.1%.

[0014] Example 2

[0015] The main chemical composition of a certain volcanic rock-type native copper deposit is as follows: SiO2 62.3%, Cu 1.15%, TFe 0.85%, Al2O3 7.6%, CaO 2.1%, MgO 1.3%, K2O 2.4%, Na2O 1.1%, and loss on ignition 1.2%. The native copper in the ore is finely embedded, ranging from 0.015 to 0.3 mm, and contains a relatively large amount of silicate impurities such as mica and feldspar.

[0016] The specific steps and parameters of the process according to this invention are as follows: (1) Crushing and staged grinding: The raw ore is coarsely crushed and medium crushed to -12mm and then fed into the ball mill. The first stage grinding produces -200 mesh (42%). After classification by a first-stage hydrocyclone, the underflow is returned to the ball mill for regrinding, and the overflow (-200 mesh, 42%) enters the second-stage hydrocyclone for classification. The final grinding fineness is -200 mesh (68%). (2) Hydrocyclone classification: The particle size of the two-stage hydrocyclone classification is 53μm. The underflow (+53μm, yield about 32%) enters gravity separation, and the overflow (-53μm, yield about 68%) enters fine flotation. (3) Spiral sluice gravity separation: feed concentration 23%, spiral sluice diameter 900mm, 4 heads. Gravity separation concentrate yield 5.8%, Cu grade 10.5%, enters shaking table for further cleaning. (4) Shaking table beneficiation: stroke 5mm, stroke rate 310 times / min, table inclination angle 3.5°. Copper concentrate yield 2.1%, Cu grade 35.2%. (5) Fine-grained native copper flotation: pH adjusted to 9.0 with lime, 120 g / t of isoamyl xanthate, and 30 g / t of No. 2 oil. One roughing, two scavenging, and two cleaning processes were performed. The yield of fine-grained copper concentrate was 0.85%, and the Cu grade was 30.8%. (6) Quartz purification: After iron removal by weak magnetic separation (1800 Oe) and strong magnetic separation (12000 Oe) of the combined tailings, reverse flotation is performed (pH adjusted to 9.5 with Na2CO3, starch 300 g / t, dodecylamine 60 g / t, one roughing and two cleaning). The reverse flotation quartz concentrate is then acid-leached with 10% hydrochloric acid at 80℃ for 2 h, with a solid-liquid ratio of 1:3, and washed until neutral.

[0017] Final product specifications: Copper concentrate: Cu grade 33.9%, copper recovery rate 82.6%; Quartz concentrate: SiO2 99.6%, TFe 0.012%, Al2O3 0.15%, CaO 0.03%, yield 55.2% (of the original ore), quartz recovery rate 88.2%.

[0018] Comparative example (traditional process)

[0019] Using the same raw ore as in Example 1, the copper was recovered using the traditional "gravity separation-flotation" single copper recovery process: grinding fineness of -200 mesh accounted for 65%, spiral sluice roughing-shaking table cleaning to recover coarse copper particles, whole pulp flotation (100g / t xanthate, pH 9.0) to recover fine copper particles, and all tailings were discharged.

[0020] Results: The copper concentrate grade was 32.1%, and the copper recovery rate was 76.8%; the tailings yield was 97.5%, of which about 70% of SiO2 was discharged into the tailings pond, and the quartz resources were not recovered and utilized.

[0021] Compared with the comparative example, Example 1 of the present invention improves the copper recovery rate by 7.4 percentage points, recovers 62.5% of the high-quality quartz concentrate from the original ore, and reduces tailings emissions by 64.1%, resulting in significant economic and environmental benefits.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for simultaneously recovering native copper and quartz from native copper ore, characterized in that, Includes the following steps: (1) Crushing and grinding: The natural copper ore is coarsely crushed and mediumly crushed and then fed into a ball mill for wet grinding. The grinding fineness is controlled so that the -200 mesh content accounts for 55% to 70% to obtain the grinding slurry. (2) Hydrocyclone classification: The grinding slurry is classified by hydrocyclone with a classification particle size of 50-74μm. The coarse particles in the underflow enter the gravity separation operation, and the fine particles in the overflow enter the fine natural copper flotation operation. (3) Spiral sluice gravity separation roughing: The underflow of the hydrocyclone is separated by spiral sluice gravity separation. The feed mass concentration is 20% to 30% to obtain gravity concentrate, gravity medium and gravity tailings. The gravity concentrate is sent to the shaking table for fine separation, the gravity medium is returned to the spiral sluice for further separation, and the gravity tailings are sent to the quartz purification operation. (4) Shaking table cleaning: The spiral sluice gravity separation concentrate is cleaned by shaking table to obtain copper concentrate, shaking table middlings and shaking table tailings; the shaking table middlings are returned to the spiral sluice for further separation, and the shaking table tailings are sent to the quartz purification operation; (5) Fine-grained native copper flotation: After the overflow of the hydrocyclone is adjusted, the fine-grained native copper is recovered by flotation. The flotation concentrate is fine-grained copper concentrate, which is combined with the shaking table copper concentrate to form the final copper concentrate product. The flotation tailings are sent to the quartz purification operation. (6) Quartz purification: The gravity separation tailings, shaking table tailings and flotation tailings are combined and purified by magnetic separation to remove iron and reverse flotation in sequence to obtain quartz concentrate; (7) Dehydration and drying: The copper concentrate and quartz concentrate are concentrated, filtered and dried respectively to obtain the final product.

2. The method according to claim 1, characterized in that: The grinding process described in step (1) adopts a staged grinding process. After grinding to -200 mesh (35% to 50%) in the first stage, the ore is classified by a hydrocyclone. The underflow is returned to the ball mill for further grinding, and the overflow enters the second stage hydrocyclone for classification.

3. The method according to claim 1, characterized in that: The separation particle size range of the spiral chute roughing in step (3) is 0.02-0.3 mm, the spiral diameter is 400-1200 mm, the number of spiral heads is 2-4, and the feed concentration ranges from 20% to 30%.

4. The method according to claim 1, characterized in that: The parameters selected for the shaking table in step (4) are: stroke 4-8mm, stroke rate 250-320 times / min, table surface inclination angle 3°-5°, and rinsing water volume 0.8-1.5L / (s·m²).

5. The method according to claim 1, characterized in that: The reagent system for the flotation of fine-grained natural copper in step (5) is as follows: lime is used as a pH adjuster to control the pulp pH to 8.0-9.5; butyl xanthate or isopentyl xanthate is used as a collector at a dosage of 60-150 g / t; No. 2 oil is used as a frother at a dosage of 15-40 g / t; the flotation process consists of one roughing, one to two scavenging and one to two cleaning.

6. The method according to claim 1, characterized in that: The magnetic separation for iron removal in step (6) adopts a combined process of weak magnetic separation and strong magnetic separation: first, weak magnetic separation with a magnetic field strength of 1000-2000 Oe is used to remove strong magnetic minerals such as magnetite, and then wet strong magnetic separation with a magnetic field strength of 8000-14000 Oe is used to remove weak magnetic minerals such as hematite, limonite, and ilmenite.

7. The method according to claim 1, characterized in that: The reagent system for reverse flotation purification in step (6) is as follows: sodium hydroxide or sodium carbonate is used to adjust the slurry and control the pH to 9.0-11.0; starch is used as a quartz inhibitor at a dosage of 150-400 g / t; sodium oleate or dodecylamine is used as a collector for mica and feldspar impurities at a dosage of 40-120 g / t; the reverse flotation process consists of one roughing and one to two cleaning stages, and the product in the tank is quartz concentrate.

8. The method according to claim 1, characterized in that: The quartz purification described in step (6) may also include an acid leaching step after reverse flotation: the reverse flotation quartz concentrate is leached with a hydrochloric acid or sulfuric acid solution with a mass fraction of 5% to 15% at 60 to 90°C for 1 to 3 hours, with a solid-liquid ratio of 1:2 to 1:

4. After leaching, it is washed until neutral to obtain high-purity quartz concentrate.

9. The method according to claim 1, characterized in that: The copper in the natural copper ore exists in the form of elemental natural copper. The ore contains 0.3% to 2.0% Cu and 55% to 80% SiO2, and the particle size of the natural copper is 0.02 to 0.5 mm.

10. The method according to claim 1, characterized in that: The final copper concentrate has a Cu grade of ≥35% and a total copper recovery rate of ≥82%; the final quartz concentrate has a SiO2 grade of ≥98.5%, an Fe2O3 content of ≤0.05%, and an Al2O3 content of ≤0.5%.

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