Method for reducing magnesium in flotation of copper-nickel sulfide ore

Abstract

The invention provides a method for reducing magnesium in flotation of copper-nickel sulfide ores, an inhibitor is added in flotation, and the inhibitor is prepared from the following components in percentage by mass: 30-40% of tannic acid, 25-35% of carboxymethyl starch, 15-20% of saponin and 10-15% of sodium lignin sulfonate. For the copper-nickel sulfide ore which easily generates a large amount of slime, floating of gangue slime is inhibited through a flotation method under the alkalescence condition that the PH value is 8-10, the flotation performance difference of the gangue slime and pentlandite is effectively increased, and the magnesium content in concentrate is conveniently and efficiently reduced. The inhibitor has the advantages of being high in inhibition performance selectivity, easy to use and the like, the content of magnesium oxide in copper-nickel sulfide ore concentrate can be effectively reduced, the quality of the concentrate is improved, and the purpose of low-grade copper-nickel sulfide ore flotation magnesium reduction is achieved.

Description

Technical Field

[0001] The invention discloses a method for reducing magnesium in the flotation of copper-nickel sulfide ore, and belongs to the field of copper-nickel sulfide ore dressing and purification technology. Background Art

[0002] ‌Copper-nickel sulfide ore‌ is mainly used to extract nickel, a metal that has important uses in the fields of military manufacturing, machinery manufacturing, modern aviation industry, atomic energy industry, etc. In addition to being the main source of nickel, copper-nickel sulfide ore is also associated with a variety of metal elements, such as copper, gold, silver, platinum, palladium, osmium, iridium, ruthenium, rhodium, cobalt, etc. These associated metals have comprehensive recovery value under technical and economic conditions.

[0003] With the continuous development of the non-ferrous metal industry, the development and utilization of copper-nickel sulfide ores have continued to deepen, and the properties of copper-nickel sulfide ores have undergone the following changes: the metal grade of the original ore has decreased, and the magnesium oxide content has increased. The hardness of the ore has decreased, and it is easy to become muddy during the grinding process, forming a mud covering the surface of the nickel pyrite, which hinders the adsorption of xanthate on the mineral surface and adhesion to the bubbles. Moreover, most of the mud has good floatability and is easy to enter the concentrate, affecting the floatability of the copper-nickel sulfide minerals, resulting in poor concentration and enrichment, an increase in the magnesium oxide content in the concentrate, and a decrease in the quality of the concentrate. Magnesium-containing silicate minerals are the most refractory components in the smelting process. When the magnesium oxide content in the concentrate exceeds 6%, the recovery rate of the smelted metal will be greatly reduced. Therefore, minimizing the magnesium content in the concentrate during the selection process is one of the important tasks of the ore dressing process. In the beneficiation of copper-nickel sulfide ores, there are many studies and applications on slime inhibitors, but the more commonly used gangue slime inhibitors are CMC, sodium hexametaphosphate, gur gum, water glass, etc., which have the disadvantages of being difficult to dilute, high cost, affecting slurry fluidity, and having poor selectivity. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for reducing magnesium in the flotation of copper-nickel sulfide ore. The present invention adds an inhibitor in the flotation reduction of copper-nickel sulfide ore. For copper-nickel sulfide ore that is prone to produce a large amount of ore mud, under weakly alkaline conditions with a pH value of 8 to 10, the flotation method is used to inhibit the floating of gangue ore mud, effectively increase the flotation performance difference between gangue ore mud and pentlandite, and facilitate efficient reduction of the magnesium content in the concentrate.

[0005] The present invention is achieved through the following technical solutions: A method for reducing magnesium in flotation of copper-nickel sulfide ore, the specific steps are as follows: Step 1: Crushing and grinding A copper-nickel sulfide ore is crushed and ground to obtain a slurry with a mass percentage concentration of 50%, wherein the content of particles below -200 mesh in the slurry accounts for 65% to 70% of the total particle size.

[0006] Step 2: Mixing the slurry The ore pulp obtained by grinding is added to a laboratory flotation machine, clean water is added to dilute the ore pulp, and the ore pulp is stirred and mixed evenly, and the slurry is adjusted, and the stirring time is 2 minutes; wherein the mass percentage concentration of the copper-nickel sulfide ore in the ore pulp is 29-33%.

[0007] Step 3: Flotation magnesium reduction After the slurry adjustment is completed, add the adjusting agent ammonium sulfate solution, the collecting agent ethyl xanthate solution, and the foaming agent butyl ammonium black medicine stock solution in sequence, and stir and mix evenly after each agent is added; then carry out a roughing operation, the scraping and foaming time is 8 to 10 minutes, and the roughing operation produces two products, namely, a roughing concentrate and a tailings; wherein the addition amount of the adjusting agent ammonium sulfate is 270 to 320 g / t of the original ore, preferably 300 g / t; the addition amount of the collecting agent ethyl xanthate is 100 to 130 g / t of the original ore, preferably 120 g / t; the addition amount of the foaming agent butyl ammonium black medicine is 30 to 40 g / t of the original ore, preferably 35 g / t.

[0008] Add the first-stage roughing concentrate to the flotation machine, add clean water and stir and mix evenly, and perform slurry adjustment, the stirring time is 2 minutes, wherein the mass percentage concentration of the copper-nickel sulfide ore in the slurry is 12-18%. After the slurry adjustment is completed, add the inhibitor, stir and mix evenly after adding the inhibitor; then perform the first-stage concentrating operation, the scraping time is 6-8 minutes, and the first-stage concentrating produces two products, the first-stage concentrating concentrate and the tailings; wherein the inhibitor addition amount is 30-70g / t of the original ore, preferably 50 g / t.

[0009] The first stage of primary concentration concentrate is added to the flotation machine, and clean water is added and stirred to mix evenly, and the slurry is adjusted, and the stirring time is 2 minutes, wherein the mass percentage concentration of the copper-nickel sulfide ore in the slurry is 8-12%. Then a second stage of secondary concentration operation is carried out, and the scraping time is 2-4 minutes. The concentrate produced by the first stage of secondary concentration is the final concentrate, and the tailings produced are tailings 3.

[0010] The inhibitor is composed of the following components in mass fraction: 30-40% tannic acid, 25-35% carboxymethyl starch, 15-20% saponin, and 10-15% sodium lignin sulfonate; the inhibitor has the characteristics of strong selectivity, easy dilution, low reagent unit consumption, safety, environmental protection, and low cost. It can effectively reduce the magnesium content in the copper-nickel concentrate, improve the concentrate quality, and enhance the beneficiation index of the sulfide copper-nickel ore.

[0011] Tannic acid (plant polyphenols) in inhibitors: extracted from gallnut or bark, complexes with metal ions (such as Mg²⁺) on the surface of gangue minerals such as serpentine through phenolic hydroxyl groups to form a hydrophobic-hydrophilic interface, inhibiting the adsorption of collectors on the mineral surface. Saponin (natural saponin): derived from the fruit of the saponin tree, adsorbed on the surface of gangue minerals such as serpentine through an amphiphilic structure, reducing its hydrophobicity and dispersing the sludge. Carboxymethyl starch (CMS): forms hydrogen bonds with the surface hydroxyl groups of gangue minerals such as serpentine through carboxyl groups, enhancing adsorption stability, and acting as a dispersant to improve the rheology of the slurry. Hydroxypropyl starch (HPS): The long-chain structure covers the active sites on the gangue surface, hinders the action of the collector, and forms a complementary adsorption layer with the plant extract. Plant polyphenols and modified starch form a complex through hydrogen bonds and electrostatic interactions, enhancing the coverage density on the surface of gangue minerals such as serpentine. The foaming properties of saponin combined with the dispersibility of starch reduce the entrainment of sludge and improve the flotation selectivity.

[0012] In the step 1, the main gangue minerals contained in a copper-nickel sulfide ore are serpentine, pyroxene, olivine and chlorite, the main metal sulfides are pyrrhotite, pentlandite and chalcopyrite, and the contents of the main Ni, Cu and Mg components are: Ni accounts for 0.6-0.9%, Cu accounts for 0.3-0.5%, and MgO accounts for 23-27%.

[0013] In the step 1, the crushing is performed by using a jaw crusher for preliminary crushing, and then a double-roll crusher is used to crush and screen the copper-nickel sulfide ore blocks to less than 2 mm.

[0014] In the step 1, grinding is performed by using a small ball mill to grind the crushed ore, the grinding medium is a 25 mm steel ball, the grinding time is 9 minutes, the grinding concentration is 50%, and the content of particles below -200 mesh in the obtained grinding product accounts for 65% to 70% of the total particle size mass.

[0015] In the step 3, the adjusting agent ammonium sulfate solution is an ammonium sulfate aqueous solution with a mass percentage concentration of 15-20%.

[0016] In the step 3, the collector ethyl xanthate solution is an ethyl xanthate aqueous solution with a mass percentage concentration of 10 to 15%.

[0017] In the step 3, the foaming agent butyl ammonium black medicine is a stock solution.

[0018] In the step 3, the stirring time after adding each reagent is 2 minutes, the inflation pressure of the roughing flotation machine is 0.3MPa, the inflation pressure of the fine flotation machine is 0.2MPa, the main shaft speed of the roughing flotation machine is 2100r / min, the main shaft speed of the fine flotation machine is 1900r / min, and the flotation machine scraper speed is 30r / min.

[0019] The present invention provides a method for reducing magnesium in flotation of sulfide copper-nickel ore. In the flotation, an inhibitor is added. For sulfide copper-nickel ore that is prone to produce a large amount of ore mud, under weakly alkaline conditions with a pH value of 8 to 10, the floating of gangue ore mud is inhibited by a flotation method, and the difference in flotation performance between gangue ore mud and pentlandite is effectively increased, so as to facilitate the efficient reduction of magnesium content in the concentrate. The inhibitor has the characteristics of strong selectivity, easy dilution, low reagent unit consumption, safety and environmental protection, low cost, etc., and can effectively reduce the magnesium content in the copper-nickel concentrate, improve the concentrate quality, and improve the beneficiation index of the sulfide copper-nickel ore. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flotation process flow chart of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further explained below with reference to specific embodiments.

[0022] Example 1 The ore sample is a copper-nickel sulfide ore sample, with a nickel grade of 0.71%, a copper grade of 0.36%, and a magnesium oxide content of 25.3%. This example compares the flotation effect of adding inhibitors and not adding inhibitors during the flotation experiment. The process flow chart of the implementation is as follows Figure 1 , specifically including the following operation process: Step 1: Crushing and grinding A copper-nickel sulfide ore was crushed and ground to obtain a slurry with a mass percentage concentration of 50%, wherein the content of particles below -200 mesh in the slurry accounted for 67% of the total particle size.

[0023] Step 2: Mixing the slurry The ore pulp obtained by grinding was added to a 1.5L flotation machine in the laboratory, clean water was added to dilute the ore pulp, and the ore pulp was stirred for 2 minutes to prepare the slurry, thereby obtaining a copper-nickel sulfide ore pulp with a mass percentage concentration of 30%.

[0024] Step 3: Flotation magnesium reduction After the slurry adjustment is completed, add the adjusting agent ammonium sulfate 300 g / t to adjust the slurry pH value to 9, the collecting agent ethyl xanthate 120 g / t, the frother butyl ammonium black powder 35 g / t, and stir for 2 minutes after adding each agent; carry out a roughing operation with a scraping and foaming time of 10 minutes. The roughing operation produces two products: a roughing concentrate and a tailings 1.

[0025] The first stage roughing concentrate was added to a 0.75L flotation machine, and water was added to dilute the pulp. The pulp was stirred for 2 minutes to obtain a copper-nickel sulfide pulp with a mass percentage concentration of 14%. 50 g / t of inhibitor was added, and after stirring for 2 minutes, a first stage concentrating operation was carried out. The scraping time was 6 minutes, and the first stage concentrating produced two products, a first stage concentrating concentrate and a tailing. The inhibitor was composed of the following components by mass fraction: 35% tannic acid, 30% carboxymethyl starch, 20% saponin, and 15% sodium lignin sulfonate.

[0026] The first stage of primary concentration concentrate was added to a 0.5L flotation machine, clean water was added to dilute the pulp, and the pulp was stirred for 2 minutes to obtain a copper-nickel sulfide pulp with a mass percentage concentration of 10%. Then a second stage of secondary concentration was carried out, and the scraping time was 2 minutes. The concentrate produced by the first stage of secondary concentration was the final concentrate, and the tailings produced were tailings 3.

[0027] Step 4: The four products obtained from the flotation experiment were dried and weighed, and their nickel, copper and magnesium oxide grades were tested.

[0028] The same flotation experiment was carried out without adding depressant before the first stage of concentration and compared with the flotation experiment with adding depressant.

[0029] The flotation concentrate indexes of Example 1 are shown in Table 1: From the data comparison in Table 1, it can be seen that when adding inhibitors during flotation, the nickel and copper grades in the concentrate are basically the same, the magnesium oxide content is reduced by 3.23%, the nickel recovery rate is increased by 3.17%, and the copper recovery rate is increased by 1.88%.

[0030] Example 2 The ore sample is a copper-nickel sulfide ore sample, with a nickel grade of 0.65%, a copper grade of 0.30%, and a magnesium oxide content of 26.50%. This example compares the flotation effect of adding an inhibitor and adding an inhibitor of sodium hexametaphosphate during the flotation experiment. The process flow chart of the implementation is as follows: Figure 1 , specifically including the following operation process: Step 1: Crushing and grinding A copper-nickel sulfide ore was crushed and ground to obtain a slurry with a mass percentage concentration of 50%, wherein the content of particles below -200 mesh in the slurry accounted for 68% of the total particle size.

[0031] Step 2: Mixing the slurry The ore pulp obtained by grinding was added to a 1.5L flotation machine in the laboratory, clean water was added to dilute the ore pulp, and the ore pulp was stirred for 2 minutes to prepare the slurry, thereby obtaining a copper-nickel sulfide ore pulp with a mass percentage concentration of 30%.

[0032] Step 3: Flotation magnesium reduction After the slurry adjustment is completed, add the adjusting agent ammonium sulfate 300 g / t to adjust the slurry pH value to 9, the collecting agent ethyl xanthate 120 g / t, the frother butyl ammonium black powder 35 g / t, and stir for 2 minutes after adding each agent; carry out a roughing operation with a scraping and foaming time of 10 minutes. The roughing operation produces two products: a roughing concentrate and a tailings 1.

[0033] The first stage roughing concentrate was added to a 0.75L flotation machine, and water was added to dilute the pulp, and the pulp was stirred for 2 minutes to obtain a copper-nickel sulfide pulp with a mass percentage concentration of 13%. 50 g / t of inhibitor was added, and after stirring for 2 minutes, a first stage concentrating operation was carried out, and the scraping time was 6 minutes. The first stage concentrating produced two products, a first stage concentrating concentrate and tailings.

[0034] The first stage of primary concentration concentrate was added into a 0.5L flotation machine, and clean water was added to dilute the pulp, and the pulp was stirred for 2 minutes to obtain a copper-nickel sulfide pulp with a mass percentage concentration of 9%. Then a second stage of secondary concentration was carried out, and the scraping time was 2 minutes. The concentrate produced by the first stage of secondary concentration was the final concentrate, and the tailings produced were tailings 3.

[0035] Step 4: The four products obtained from the flotation experiment were dried and weighed, and their nickel, copper and magnesium oxide grades were tested.

[0036] The same flotation experiment was carried out by adding 50 g / t sodium hexametaphosphate as an inhibitor before the first stage of concentration, and compared with the flotation experiment with the addition of the inhibitor.

[0037] The flotation concentrate indexes of Example 2 are shown in Table 2: From the data comparison in Table 2, it can be seen that the addition of inhibitors during flotation can keep the nickel and copper grades in the concentrate basically the same, the magnesium oxide content is reduced by 1.67%, the nickel recovery rate is increased by 1.15%, and the copper recovery rate is increased by 0.71%.

Claims

1. A method for reducing magnesium in flotation of copper-nickel sulfide ore, comprising the following steps: Step 1: Crushing and grinding Crushing and grinding the copper-nickel sulfide ore to obtain a slurry with a mass percentage concentration of 40-60%; wherein the content of particles below -200 mesh in the slurry accounts for 65%-70% of the total particle mass; Step 2: Mixing the slurry The ore pulp obtained by grinding is added to the flotation equipment, clean water is added to dilute the ore pulp, and the ore pulp is stirred and mixed evenly, and the slurry is adjusted, and the stirring time is 2 to 5 minutes; wherein the mass percentage concentration of the copper-nickel sulfide ore in the ore pulp after slurry adjustment is 29 to 33%; Step 3: Flotation magnesium reduction After the slurry is adjusted, add the adjusting agent ammonium sulfate solution, the collecting agent ethyl xanthate solution, and the foaming agent butyl ammonium black medicine stock solution in turn, and stir and mix evenly after each agent is added; then carry out a roughing operation, the scraping and foaming time is 8 to 10 minutes, and the roughing operation produces two products, a roughing concentrate and a tailing; the addition amount of the adjusting agent ammonium sulfate is 270 to 320 g / t of the original ore, the addition amount of the collecting agent ethyl xanthate is 100 to 130 g / t of the original ore, and the addition amount of the foaming agent butyl ammonium black medicine is 30 to 40 g / t of the original ore; Adding a first-stage roughing concentrate to a flotation device, adding clean water and stirring and mixing evenly, and performing slurry adjustment, wherein the mass percentage concentration of the copper-nickel sulfide ore in the slurry after slurry adjustment is 12-18%; after the slurry adjustment is completed, adding an inhibitor, stirring and mixing evenly after adding the inhibitor; then performing a first-stage concentrating operation, the scraping and foaming time is 6-8 minutes, and the first-stage concentrating produces two products, namely, a first-stage concentrating concentrate and tailings; wherein the inhibitor addition amount is 30-70g / t of raw ore; the inhibitor is composed of the following components by mass fraction: 30-40% tannic acid, 25-35% carboxymethyl starch, 15-20% saponin, and 10-15% sodium lignin sulfonate; The first stage concentrated ore is added into the flotation equipment, clean water is added and stirred to mix evenly, and slurry is adjusted, wherein the mass percentage concentration of the copper-nickel sulfide ore in the slurry after slurry adjustment is 8-12%; then a second stage of concentration operation is carried out, the scraping time is 2-4 minutes, the concentrate produced by the first stage of concentration is the final concentrate, and the tailings produced are tailings 3.

2. The method for reducing magnesium in flotation of copper-nickel sulfide ore according to claim 1, characterized in that: In step 1, the main gangue minerals contained in the copper-nickel sulfide ore are serpentine, pyroxene, olivine and chlorite, the main metal sulfides are pyrrhotite, pentlandite and chalcopyrite, and the contents of Ni, Cu and Mg components are: Ni accounts for 0.6-0.9%, Cu accounts for 0.3-0.5%, and MgO accounts for 23-27%.

3. The method for reducing magnesium in flotation of copper-nickel sulfide ore according to claim 1, characterized in that: In step 1, the crushing is performed by using a jaw crusher for preliminary crushing, and then a double-roll crusher is used to crush and screen the copper-nickel sulfide ore blocks to less than 2 mm.

4. The method for reducing magnesium in flotation of copper-nickel sulfide ore according to claim 1, characterized in that: In step 1, the grinding medium is a 25 mm steel ball, the grinding time is 9 min, the grinding concentration is 50%, and the content of particles below -200 mesh in the obtained grinding product accounts for 65% to 70% of the total particle size mass.

5. The method for reducing magnesium in flotation of copper-nickel sulfide ore according to claim 1, characterized in that: In step 3, the adjusting agent ammonium sulfate solution is an ammonium sulfate aqueous solution with a mass percentage concentration of 15-20%.

6. The method for reducing magnesium in flotation of copper-nickel sulfide ore according to claim 1, characterized in that: In step 3, the collector ethyl xanthate solution is an ethyl xanthate aqueous solution with a mass percentage concentration of 10 to 15%.

7. The method for reducing magnesium in flotation of copper-nickel sulfide ore according to claim 1, characterized in that: In step 3, the stirring time after adding each reagent is 2-5 minutes, the inflation pressure of the roughing flotation machine is 0.3MPa, the inflation pressure of the fine flotation machine is 0.2MPa, the main shaft speed of the roughing flotation machine is 2100r / min, the main shaft speed of the fine flotation machine is 1900r / min, and the scraper speed of the flotation machine is 30r / min.

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