Fluorine-free and acid-free method for recovering high-grade quartz from sulfide tailings

Abstract

The invention discloses a fluoride-free and acid-free method for recycling high-grade quartz from sulfide tailings, and belongs to the technical field of comprehensive utilization of mineral resources. According to the method, through the technical route of directional grading pretreatment and fluoride-free and acid-free collaborative reverse flotation separation, the separation problem of quartz and gangue minerals in the sulfide tailings is effectively solved, the quartz concentrate with the SiO2 grade larger than or equal to 90% is obtained, the cost of a beneficiation reagent per unit quartz concentrate is smaller than 50 yuan / ton, and the standard requirements of the glass and ceramic industry are met. The method not only improves the quartz recovery rate, but also effectively avoids fluoride and acid wastewater pollution in the traditional process, has good environmental protection property and economical efficiency, is suitable for large-scale industrial production, and provides a new technical solution for resource utilization of the sulfide tailings.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive resource utilization technology, specifically relating to a method for recovering high-grade quartz from sulfide tailings without fluorine or acid. Background Technology

[0002] my country's sulfide mines generate a massive annual tailings discharge. Given the principle of "only reducing, not increasing" tailings ponds, many currently in-use tailings ponds have only a short remaining service life, making the resource utilization of tailings an urgent priority. Non-metallic minerals account for over 90% of sulfide tailings, with quartz, a major silicon-containing mineral, often coexisting with gangue minerals such as calcite and feldspar. Their surface physicochemical properties are quite similar, making separation difficult. The glass and ceramics industries have stringent requirements for the impurity content of quartz raw materials. According to the standards "Quartz Sand for Glass" (GB / T 32643-2016) and "Quartz Powder for Ceramics" (GB / T 40665-2021), quartz sand for glass requires a feldspar (calculated as K2O+Na2O) content of ≤1.0%, and quartz for ceramics requires ≤1.5%. There are also strict limits on the content of carbonate minerals such as calcite. Incomplete impurity removal can lead to increased glass melting temperatures and deformation of ceramic products, severely impacting product quality.

[0003] Analysis of existing flotation separation processes for quartz and gangue minerals in tailings reveals three major shortcomings that prevent them from meeting the quartz recovery requirements of sulfide tailings: (1) Low quartz-gangue separation efficiency and difficulty in achieving quartz grade standards: Existing direct flotation processes mostly use sodium oleate as a collector to directly collect quartz, failing to fully utilize the selectivity differences of the reagents for different gangue minerals, resulting in severe co-flotation of quartz with calcite and feldspar. Publicly available test data show that the feldspar (K2O+Na2O) content in the quartz concentrate after flotation is still 2.0%~3.5%, and the content of calcite-related impurities (calculated as CaO) often exceeds 2.0%, far exceeding the industry standard, making it unsuitable as a direct industrial raw material. Some processes use hydrofluoric acid to activate the quartz surface to enhance separation, but hydrofluoric acid can lead to a fluoride concentration of 15~30 mg / L in the mineral processing wastewater, far exceeding the limit of 10 mg / L in the "Surface Water Environmental Quality Standard" (GB 3838-2002), and fluoride ions will react with Ca in the tailings. 2+ Mg 2+ It forms sediment that adheres to the inner wall of the equipment, causing pipeline blockage. It also poses occupational health risks to operators and presents significant environmental and safety hazards.

[0004] (2) Dependence on acidic conditions, leading to significant equipment corrosion and pollution problems: Existing fluorine-free processes often use sulfuric acid to adjust the pH to 3-5 to enhance the selectivity of the collector for quartz. However, the acidic environment causes two problems. On the one hand, reagent consumption surges, and Fe in the tailings increases. 3+ Al3+ It forms stable complexes with sodium oleate, leading to a 30%–50% increase in sodium oleate consumption compared to a neutral environment. Furthermore, the complexes coat the surface of gangue minerals, reducing the reagent's collection efficiency. Public data shows that its feldspar removal rate is only 65%–72%, and the calcite removal effect is also unsatisfactory. On the other hand, equipment wear and wastewater treatment costs are high: acidic media accelerates the corrosion of the stainless steel lining of the flotation machine, with a corrosion rate reaching 0.3 mm / year, shortening the equipment replacement cycle to 2–3 years. Taking a thousand-ton-level production line as an example, the average annual equipment maintenance cost exceeds 2 million yuan; simultaneously, the generated acidic wastewater requires alkali neutralization treatment, with treatment costs reaching 8–12 yuan / ton, further increasing production costs.

[0005] (3) Fine-grained interference exacerbates separation difficulty and results in low quartz recovery: -75μm fine-grained particles account for 30%~45% of lead-zinc sulfide tailings, and the particle size difference between calcite, feldspar and quartz in the fine-grained particles is smaller and the surface adsorption is stronger. The existing process does not design a graded pretreatment for this characteristic. Fine-grained gangue minerals are easy to cover the surface of coarse-grained quartz, which hinders the inhibitory effect of the inhibitor on quartz. At the same time, fine-grained quartz is easy to float with gangue mineral foam, resulting in a quartz retention rate of only 70%~78% in the tailings. This not only reduces the quartz recovery rate, but also reduces the purity of gangue mineral collection due to the mixing of fine-grained quartz with foam, forming a double contradiction of "separation efficiency-recovery rate".

[0006] Therefore, it is essential to develop a product and method that can solve the above-mentioned technical problems. Summary of the Invention

[0007] The purpose of this invention is to provide a method for recovering high-grade quartz from sulfide tailings without fluorine or acid.

[0008] The objective of this invention is achieved as follows: the method for recovering high-grade quartz from sulfide tailings without fluorine or acid includes pretreatment and synergistic reverse flotation steps, specifically including: A. Preprocessing: 1) The sulfide tailings to be treated are separated into +75μm coarse-grained tailings a and -75μm fine-grained tailings b using a classification device; 2) Add water to the +75μm coarse-grained tailings a to prepare a slurry c with a concentration of 20~25%; B. Collaborative reverse flotation: 1) Add water glass and magnesium sulfate to slurry c, stir for 2-4 minutes at a speed of 900-1000 r / min, then add sodium oleate, stir for 4-6 minutes at a speed of 900-1000 r / min, and then perform roughing to obtain bottom product rough quartz concentrate d and tailings e. 2) Add water glass and magnesium sulfate to the bottom product rough quartz concentrate d, stir for 2-4 minutes, then add sodium oleate and stir for 4-6 minutes to perform a first scavenging to obtain the bottom product first scavenging quartz concentrate f and tailings g; 3) Add water glass and magnesium sulfate to the bottom product f of the quartz concentrate, stir for 2-4 minutes, then add sodium oleate and stir for 4-6 minutes to obtain the bottom product h of the final quartz concentrate and tailings i.

[0009] The specific steps are as follows: Step 1: Tailings Directional Classification Pretreatment – ​​Eliminating Fine Particle Interference Sulfide tailings with an initial SiO2 grade of 45%~55%, feldspar (K2O+Na2O) content of 3.5%~6.5%, calcite content of about 15%, and impurities such as Zn, Pb, and Fe were selected and particle size was classified using hydraulic classification equipment (such as hydrocyclones in production and standard sieves in the laboratory).

[0010] (1) The classification threshold is set to 75μm. The classification equipment can achieve efficient separation of +75μm coarse tailings and -75μm fine tailings. (2) Directly discard the -75μm fine-grained tailings (accounting for 45%~65% of the original tailings). In this grade, the particle size difference between calcite, feldspar and quartz is less than 5μm. The selective collection of sodium oleate for the three is only 1.2~1.5 times, making separation extremely difficult. Retain the +75μm coarse-grained tailings as reverse flotation raw material. The particle size difference between quartz and calcite and feldspar is ≥10μm. The selective collection coefficient of sodium oleate for gangue minerals is increased to 2.8~3.2 times, and the content of impurities such as Fe and Zn is reduced to below 1.8%, avoiding interference of impurities with the action of reagents.

[0011] Step 2: Fluorine-free and acid-free synergistic reverse flotation separation – sodium oleate collects gangue + magnesium sulfate strengthens water glass to suppress quartz.

[0012] The +75μm coarse-grained tailings obtained in step 1 are mixed with tap water, and the mass ratio of tailings to water is adjusted to prepare a slurry with a concentration of 20%~25%. The "one coarse and two scavenging" open-circuit reverse flotation process is adopted. No fluoride reagents or acid-base adjusters are added throughout the process. The pH is maintained at 7.0 (neutral) by the slurry's own buffer system. The core is to use sodium oleate to preferentially collect calcite and feldspar and remove them with the froth, while magnesium sulfate reinforced glass inhibits the retention of quartz in the tailings at the bottom of the tank. In the roughing stage, water glass (400-600 g / t) and magnesium sulfate (350-550 g / t) are added simultaneously and stirred for 2-4 minutes. Then, sodium oleate (500-800 g / t) is added and stirred for 3-5 minutes before flotation, which takes 3-7 minutes. In the scavenging stage, water glass (200-300 g / t) and magnesium sulfate (150-250 g / t) are added simultaneously and stirred for 2-4 minutes. Then, sodium oleate (200-400 g / t) is added and stirred for 3-5 minutes before flotation, which takes 1-3 minutes.

[0013] The order of reagent addition in this invention (adding the inhibitor first, followed by thorough stirring) is carefully designed. Its purpose is to: firstly, ensure sufficient Mg... 2+ It rapidly forms an active ionic polymer with water glass and preferentially adsorbs onto the quartz surface, completing the main inhibition function. Subsequently, under the action of the collector sodium oleate, a large amount of Ca is stripped from the calcite surface and released. 2+ At this point, the main inhibition task has been completed, and the subsequently generated CaSO4 mainly plays the aforementioned auxiliary enhancing role. This time-difference design based on reaction kinetics ensures the effective functioning of the core agent mechanism and transforms potential side reactions into beneficial supplements.

[0014] Drug synergistic mechanism Synergistic effect of magnesium sulfate and water glass: Mg in magnesium sulfate 2+ As a weak alkali metal ion, it can react with the water glass hydrolysis product SiO(OH)3. - The reaction generates an ionic polymer, which is adsorbed onto the quartz surface via weak physical adsorption. Simultaneously, water glass forms stable silicon-oxygen bonds (Si-O-Si) with the Si-OH groups on the quartz surface, together forming a hydrophilic film 8-10 nm thick (contact angle <20°) on the quartz surface. This strongly inhibits quartz flotation, ensuring its retention in the tailings. Meanwhile, the calcite surface mainly exposes Ca... 2+ Active sites, water glass and its interaction with Mg 2+The polymer adsorbs only one-quarter of that on the calcite surface compared to quartz, and its adsorption strength is low (the fixation energy is only 15%~20% of that on the quartz surface), failing to form an effective hydrophilic film and thus not affecting its buoyancy. This selectivity difference is consistent with the adsorption characteristics of water glass on different mineral surfaces, and studies have shown that its fixation strength on the quartz surface is significantly higher than that on calcium and magnesium minerals such as calcite.

[0015] Under the neutral slurry environment and specific reagent addition sequence and stirring conditions set in this invention, MgSO4 and Ca 2+ The reaction is limited and controllable. This reaction not only does not weaken the core inhibition mechanism, but also synergistically enhances the inhibition of quartz through the following two pathways: ① The trace amounts of CaSO4 precipitate generated exhibit preferential affinity for the quartz surface. These microcrystals are physically adsorbed onto the quartz surface, reacting with the subsequently added water glass hydrolysis product SiO(OH)3. - and Mg 2+ The generated ionic polymers collectively construct a thicker, denser hydrophilic film. This "composite hydrophilic film," compared to films formed from single components, exhibits higher stability and coverage, thus significantly enhancing the quartz suppression effect. ② Free Ca in the slurry 2+ These are "harmful ions" that cause a decrease in flotation selectivity. They non-selectively activate various silicate minerals, including quartz, and may undergo unwanted side reactions with collectors such as sodium oleate. In this invention, the addition of MgSO4 preferentially consumes this portion of "harmful" free Ca. 2+ The precipitate is fixed as an inert CaSO4 precipitate. This process "purifies" the pulp liquid phase, reduces interference with the calcite flotation process, and thus indirectly improves the selective collection efficiency of sodium oleate for calcite and feldspar.

[0016] Selective harvesting of sodium oleate: Sodium oleate is harvested in neutral environments as carboxylate (-COO-) - It exists in the form of Ca on the surface of calcite. 2+ The binding energy can reach -460.80 kJ / mol, which is much higher than that of Si on the quartz surface. 4+ The binding energy (-23.4 kJ / mol) of sodium oleate allows for preferential adsorption on the calcite surface due to the strong chemical bonding. Under natural pH conditions, 15 mg / L sodium oleate can achieve a calcite recovery rate exceeding 90%, while the quartz recovery rate is less than 20% under the same conditions, further confirming that sodium oleate's collection efficiency for calcite is more than 2.8 times that of quartz. Simultaneously, sodium oleate binds to the K+ on the feldspar surface... + Na + The binding energy (-58.6 kJ / mol) is also significantly higher than that of quartz, thus enabling the simultaneous preferential collection of the two gangue minerals, forming a hydrophobic layer (contact angle > 60°), which allows them to float and separate with the foam.

[0017] Step 3: Quartz tailings enrichment, recovery and post-processing The product from the second scavenging tank obtained in step 2 is sent to a vacuum filter for dewatering, controlling the filter cake moisture content to be <15%, to obtain the final quartz concentrate. The final quartz concentrate is subjected to compositional analysis, and the core indicators meet the following requirements: SiO2 grade ≥90%, up to 95.12%; SiO2 graded recovery rate ≥85%; total SiO2 recovery rate ≥30% (based on the total amount of SiO2 in the original sulfide tailings); The content of feldspar impurities (K2O+Na2O) is ≤1.0%, and the content of calcite-related impurities is ≤0.8%, which fully meets the standards for quartz sand used in glassmaking; other impurities are Fe≤0.32%, Pb≤0.065%, Zn≤0.060%, and there are no fluoride residues.

[0018] The tailings water quality has a pH value of 6-9, a COD concentration of <50mg / L, and a fluoride concentration of <5mg / L.

[0019] Technical points of this invention: (1) Innovative separation mechanism: For the first time, a synergistic reverse flotation separation path was clearly defined, in which sodium oleate preferentially collects calcite and feldspar, while magnesium sulfate-reinforced water glass inhibits quartz from remaining in the tailings. This breaks through the technical limitations of traditional processes that only target a single gangue mineral or a single reagent. By utilizing the high selectivity of sodium oleate for gangue minerals (the collection efficiency for calcite is 2.8 times that for quartz and 3.0 times that for feldspar) and the strong inhibition of magnesium sulfate-water glass on quartz (the adsorption capacity is 4 times that of gangue minerals), the simultaneous and efficient separation of quartz from calcite and feldspar is achieved, and the total removal rate of gangue minerals is increased to over 92%.

[0020] (2) Innovation of the synergistic drug system: A synergistic inhibition system is innovatively introduced by combining magnesium sulfate and water glass. 2+ The ionic polymers generated by the reaction with the hydrolysis products of water glass can form a thicker and more stable hydrophilic film on the quartz surface, improving the quartz inhibition effect by more than 40% compared to water glass alone. Simultaneously, considering the symbiotic characteristics of gangue minerals in sulfide tailings, a stepped scheme was determined, using 500g / t of water glass, 400g / t of magnesium sulfate, and 700g / t of sodium oleate in the roughing stage, while halving the amount of scavenging reagents. This ensures sufficient collection of gangue minerals and strong quartz inhibition in the roughing stage, while avoiding quartz entrainment caused by excessive reagents in the scavenging stage. Compared to existing processes, the reagent utilization rate is increased by 30%, and the reagent cost per unit quartz concentrate is only 42.8 yuan.

[0021] (3) Collaborative innovation of classification-reverse flotation: 75μm is clearly defined as the key classification threshold for separating quartz from gangue minerals. The -75μm fine-grained tailings are discarded, eliminating the "covering effect" of fine-grained gangue minerals on the quartz surface and the "entraining effect" of fine-grained quartz. This increases the SiO2 recovery rate of quartz tailings after reverse flotation by 10%~12% and the gangue mineral removal rate by 8%~10% compared to the unclassified process, while also resolving the contradiction between "separation efficiency and recovery rate" caused by fine-grained particles.

[0022] The beneficial effects of this invention are: (1) Outstanding environmental friendliness: The entire process is free of fluoride and acid, the fluoride concentration in the mineral processing wastewater is <0.8mg / L (far below the national standard limit of 10mg / L), the pH is maintained at 7.0 neutral, and there is no need to build fluoride / acid and alkali wastewater treatment facilities. The annual environmental protection investment of the thousand-ton production line is reduced by 600,000 to 900,000 yuan. The neutral environment reduces the corrosion rate of flotation equipment by 85% and extends the service life of equipment to 6 to 8 years, which is 2 to 3 times higher than the traditional acidic process.

[0023] (2) Excellent quartz quality and recovery rate: The final quartz concentrate has SiO2 ≥ 90%, feldspar (K2O+Na2O) ≤ 1.0%, and calcite-related impurities ≤ 0.8%, which fully meets the high-end demand of the glass and ceramics industry. The market price is RMB 300~800 / ton, which significantly increases the value of resources compared with the original tailings stockpiling (cost RMB 15~20 / ton); the SiO2 recovery rate is ≥ 90%, which is 12%~15% higher than the existing process, and the resource utilization rate is significantly improved.

[0024] (3) Significant technical and economic benefits: The "one roughing and two sweeping" reverse flotation process does not require multiple stages of fine cleaning, reducing equipment investment by 35%; the unit cost of quartz concentrate reagents is less than RMB 50, which is 40% lower than that of fluorine-containing processes; and the comprehensive cost per ton of concentrate is controlled within RMB 100.

[0025] (4) Wide adaptability: It is specifically designed for the associated characteristics of quartz, calcite and feldspar in sulfide tailings, solving the problem of poor adaptability of traditional processes to the separation of this type of tailings. At the same time, it can be extended to the treatment of other non-ferrous metal tailings containing quartz-carbonate-feldspar, with a wide range of application scenarios. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a schematic diagram of the main phase analysis of the sulfide tailings in Example 1 of the present invention; Figure 3 This is a schematic diagram of the main phase analysis of quartz concentrate in Example 1 of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0028] The method for recovering high-grade quartz from sulfide tailings without fluorine or acid, as described in this invention, includes pretreatment and synergistic reverse flotation steps, specifically including: A. Preprocessing: 1) The sulfide tailings to be treated are separated into +75μm coarse-grained tailings a and -75μm fine-grained tailings b using a classification device; 2) Add water to the +75μm coarse-grained tailings a to prepare a slurry c with a concentration of 20~25%; B. Collaborative reverse flotation: 1) Add water glass and magnesium sulfate to slurry c, stir for 2-4 minutes at a speed of 900-1000 r / min, then add sodium oleate, stir for 4-6 minutes at a speed of 900-1000 r / min, and then perform roughing to obtain bottom product rough quartz concentrate d and tailings e. 2) Add water glass and magnesium sulfate to the bottom product rough quartz concentrate d, stir for 2-4 minutes, then add sodium oleate and stir for 4-6 minutes to perform a first scavenging to obtain the bottom product first scavenging quartz concentrate f and tailings g; 3) Add water glass and magnesium sulfate to the bottom product f of the quartz concentrate, stir for 2-4 minutes, then add sodium oleate and stir for 4-6 minutes to obtain the bottom product h of the final quartz concentrate and tailings i.

[0029] Step B, 1) The amount of water glass added is 400~600g / t.

[0030] In step B, the amount of magnesium sulfate added is 350~550g / t.

[0031] In step B, the amount of sodium oleate added is 500~800g / t.

[0032] Step B, 2) The amount of water glass added is 200~300g / t.

[0033] In step B, the amount of magnesium sulfate added is 150~250g / t.

[0034] In step B, the amount of sodium oleate added is 200~400g / t.

[0035] Step B, 3) The amount of water glass added is 200~300g / t.

[0036] In step B, the amount of magnesium sulfate added is 150~250g / t.

[0037] In step B, the amount of sodium oleate added is 200~400g / t.

[0038] The invention will be further illustrated below with specific implementation examples: Example 1 and Comparative Example 1 Both Example 1 and Comparative Example 1 used a lead-zinc sulfide tailings from Yunnan Province as the treatment object. The main phase analysis of the sulfide tailings is shown in [reference needed]. Figure 2 The main chemical components (mass fraction) of the tailings are as follows: Zn 1.71%, Pb 0.17%, CaO 17.59% (mainly from calcite), SiO2 54.69%, feldspar (K2O+Na2O) 5.8%, Fe 2.23%, Al2O3 3.65%, S 1.98%.

[0039] The specific steps for recovering quartz using the method of this invention are as follows: (1) Directional classification pretreatment: Using a 200-mesh standard sieve, +75μm coarse-grained tailings (yield 42%) and -75μm fine-grained tailings (yield 58%) were separated. In Example 1, the +75μm coarse-grained tailings were used for subsequent operations, and the SiO2 grade of the +75μm coarse-grained tailings was increased to 68.52%, the feldspar (K2O+Na2O) content was reduced to 4.5%, and the CaO content was reduced to 12.1%. In Comparative Example 1, the -75μm fine-grained tailings were used for subsequent operations, in which the SiO2 grade was 44.67%, the feldspar (K2O+Na2O) content was 6.74%, and the CaO content was 21.57%.

[0040] (2) Preparation of slurry: In both Example 1 and Comparative Example 1, the coarse and fine tailings after classification were mixed with tap water at a mass ratio of 3.5:1 to prepare a slurry with a concentration of 22%.

[0041] (3) Both Example 1 and Comparative Example 1 carried out fluorine-free and acid-free synergistic reverse flotation separation. ① Roughing: Add 500g / t water glass and 400g / t magnesium sulfate to the slurry and stir for 3 minutes (950r / min); then add 700g / t sodium oleate and stir for 5 minutes; use an XFD-1.5L flotation machine, control the rotation speed at 2000r / min and the air flow rate at 0.22Nm³ / h, and float for 4 minutes to obtain the bottom product, rough quartz concentrate. Continue scavenging to improve the grade of quartz concentrate.

[0042] ② First scavenging: Add 300g / t water glass and 200g / t magnesium sulfate to the remaining slurry from the roughing stage, stir for 3 minutes; then add 350g / t sodium oleate, stir for 5 minutes, and float for 2.5 minutes according to the roughing parameters. The bottom product after the first scavenging is the first scavenged quartz concentrate, and scavenging continues.

[0043] ③ Second scavenging: Add 300g / t water glass and 200g / t magnesium sulfate to the slurry remaining from the first scavenging, stir for 3min; then add 350g / t sodium oleate, stir for 5min, and float for 2.5min according to the roughing parameters. The bottom product after the second scavenging is the final quartz concentrate.

[0044] Example 1: The final quartz concentrate had a SiO2 grade of 91.21%, feldspar (K2O+Na2O) of 0.8%, CaO of 0.36%, Fe of 0.32%, Pb of 0.065%, and Zn of 0.060%. The main phase analysis of the quartz concentrate is shown below. Figure 3 The SiO2 recovery rate was 85.66%, and the unit concentrate reagent cost was 34.65 yuan. Comparative Example 1: Quartz concentrate SiO2 grade 61.28%, feldspar (K2O+Na2O) 3.11%, CaO 6.02%, Fe 2.39%, Pb 0.15%, Zn 0.92%; Tailings water quality test results: Example 1 water quality test results were pH=7.62, COD concentration was 32mg / L, and fluoride concentration was 1.57mg / L; Comparative Example 1 water quality test results were pH=8.16, COD concentration was 28mg / L, and fluoride concentration was 0.92mg / L.

[0045] Example 2 and Comparative Example 2 Both Example 2 and Comparative Example 2 use a lead-zinc sulfide tailings from Yunnan as the treatment object. The initial grade of the tailings is 48.07% SiO2, 6.22% feldspar (K2O+Na2O), 10.86% CaO, 1.56% Fe, and 2.87% Al2O3.

[0046] Example 2 uses the method of the present invention to recover quartz. The specific steps are as follows: (1) Directional classification pretreatment: Using a 200-mesh standard sieve, +75μm coarse-grained tailings (yield 35%) were separated, and -75μm fine-grained tailings were discarded; the SiO2 grade of the +75μm coarse-grained tailings was increased to 67.10%, the feldspar (K2O+Na2O) content was reduced to 2.8%, and the CaO content was reduced to 6.5%.

[0047] (2) Preparation of slurry: Mix +75μm coarse-grained tailings with tap water at a mass ratio of 3:1 to prepare a slurry with a concentration of 25%.

[0048] (3) Fluorine-free and acid-free synergistic reverse flotation separation: ① Roughing: Add 400g / t water glass and 350g / t magnesium sulfate to the slurry and stir for 2.5min (950r / min); then add 600g / t sodium oleate and stir for 5min; use an XFD-1.5L flotation machine, controlling the rotation speed at 2000r / min and the air flow rate at 0.22Nm. 3 Flotation was carried out at a rate of 6 h for 6 min to obtain the bottom product, rough quartz concentrate. Scavenging was then carried out to improve the grade of the quartz concentrate.

[0049] ② First scavenging: Add 200g / t water glass and 175g / t magnesium sulfate to the remaining slurry from the roughing stage, stir for 2.5min; then add 300g / t sodium oleate, stir for 5min, and float for 2min according to the roughing parameters. The bottom product after the first scavenging is the first scavenged quartz concentrate, and scavenging continues.

[0050] ③ Second scavenging: Add 200g / t water glass and 150g / t magnesium sulfate to the slurry remaining from the first scavenging, stir for 2.5min; then add 300g / t sodium oleate, stir for 5min, and float for 1.5min according to the roughing parameters. The bottom product after the second scavenging is the final quartz concentrate.

[0051] Comparative Example 2: Steps (1) and (2) are the same as in Example 2; Step (3) is performed under the same conditions as in Example 2, except that magnesium sulfate is not added to the reagent.

[0052] In Example 2, the final quartz concentrate contained 87.58% SiO2, 0.9% feldspar (K2O+Na2O), and 0.7% CaO, with a SiO2 recovery rate of 89.08%. In Comparative Example 2, the final quartz concentrate contained 80.12% SiO2, 2.22% feldspar (K2O+Na2O), and 3.61% CaO, with a SiO2 recovery rate of 83.84%.

Claims

1. A method for recovering high-grade quartz from sulfide tailings without fluorine or acid, characterized in that, The method for recovering high-grade quartz from sulfide tailings without fluorine or acid includes pretreatment and synergistic reverse flotation steps, specifically including: A. Preprocessing: 1) The sulfide tailings to be treated are separated into +75μm coarse-grained tailings a and -75μm fine-grained tailings b using a classification device; 2) Add water to the +75μm coarse-grained tailings a to prepare a slurry c with a concentration of 20~25%; B. Collaborative reverse flotation: 1) Add water glass and magnesium sulfate to slurry c, stir for 2-4 minutes at a speed of 900-1000 r / min, then add sodium oleate, stir for 4-6 minutes at a speed of 900-1000 r / min, and then perform roughing to obtain bottom product rough quartz concentrate d and tailings e. 2) Add water glass and magnesium sulfate to the bottom product rough quartz concentrate d, stir for 2-4 minutes, then add sodium oleate and stir for 4-6 minutes to perform a first scavenging to obtain the bottom product first scavenging quartz concentrate f and tailings g; 3) Add water glass and magnesium sulfate to the bottom product f of the quartz concentrate, stir for 2-4 minutes, then add sodium oleate and stir for 4-6 minutes to obtain the bottom product h of the final quartz concentrate and tailings i.

2. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, Step B, 1) The amount of water glass added is 400~600g / t.

3. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, In step B, the amount of magnesium sulfate added is 350~550g / t.

4. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, In step B, the amount of sodium oleate added is 500~800g / t.

5. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, Step B, 2) The amount of water glass added is 200~300g / t.

6. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, In step B, the amount of magnesium sulfate added is 150~250g / t.

7. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, In step B, the amount of sodium oleate added is 200~400g / t.

8. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, Step B, 3) The amount of water glass added is 200~300g / t.

9. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, In step B, the amount of magnesium sulfate added is 150~250g / t.

10. The method for recovering high-grade quartz from sulfide tailings without fluorine or acid according to claim 1, characterized in that, In step B, the amount of sodium oleate added is 200~400g / t.

Images