Method for preparing refined calcite powder through combination of dressing and smelting of limestone ore

Abstract

The invention discloses a method for preparing refined calcite powder by combining limestone ore dressing and smelting. According to the dissemination characteristic of the limestone ore, the technology of ore grinding, scrubbing, magnetic separation, reverse flotation impurity removal, direct flotation concentration and reduction leaching is designed, the flotation reagent system is improved, and a multi-stage flotation mode is provided according to the occurrence form of limestone ore impurities, that is, easy-to-float gangue minerals are floated out firstly, and then the limestone ore impurities are separated out; and gangue minerals difficult to float are inhibited. And a scheme for reducing and leaching by using thiourea dioxide is provided for flotation concentrate which is high in calcium oxide content but does not meet the requirements of refined calcite powder products, so that the requirements of the refined calcite powder products are met. And finally, the refined calcite powder product with the CaO content being 54% or above and the Fe2O3 content being 0.05% or below is obtained, equipment used in the method is conventional preparation equipment, the technological process is simple, and industrial large-scale production is easy.

Description

Technical Field

[0001] The invention relates to the technical field of rational utilization and hydrometallurgy of limestone ore, and in particular to a method for preparing refined calcite powder by combining limestone ore dressing and smelting. Background Art

[0002] Refined calcite powder has a wide range of uses and is widely used in natural rubber, synthetic rubber, paint and papermaking, cables, coatings, cosmetics and other industries. In addition to the significant advantage of reducing costs, refined calcite powder can also improve the processing performance and mechanical properties of plastic products, increase the gloss of coatings, paints and paper, and play a reinforcing role. At the same time, refined calcite powder is also often used in the addition of coatings and pulp. However, in its actual application process, refined calcite powder often faces various problems, such as a large number of impurities. The types and contents of impurities in refined calcite powder are mainly reflected in the appearance of its powder. When the iron content in the calcite powder is high, the appearance of the calcite powder will appear yellow; when the magnesium content is high, the appearance of the calcite powder will appear gray. The presence of various impurities will lead to a decrease in the whiteness of the powder. Calcite powder that is not impurity-removed often has a high content of acid-insoluble matter, which will directly affect the processing of subsequent high-value-added products; if the product is used as a filler for rubber, the impurities will directly affect the various properties of the filled product. Therefore, it is necessary to remove impurities and purify by means of mineral processing.

[0003] Patent A process for removing impurities from calcite ore to improve whiteness (CN116651600A) discloses a method of using photoelectric beneficiation to remove impurities and improve whiteness, but there are energy loss problems such as high energy consumption. Existing methods of whitening calcite include introducing titanium dioxide or fluorescent whitening, which have good effects but are too expensive to be used in practice. Removing impurities through beneficiation to prepare refined calcite powder has low cost, high efficiency, no environmental pollution, and good application prospects and economic benefits. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing refined calcite powder by limestone ore dressing and smelting, which adopts the process of grinding-scrubbing-magnetic separation-reverse flotation impurity removal-positive flotation concentration-reduction leaching to treat the limestone ore, enrich the impurity gangue minerals into tailings, and realize the efficient separation and enrichment of limestone ore dressing and impurity removal.

[0005] The present invention provides a method for preparing refined calcite powder by combining limestone ore dressing and smelting, comprising the following steps:

[0006] S1. Crushing and grinding the limestone ore to obtain mineral powder;

[0007] S2. The mineral powder obtained in step S1 is scrubbed to obtain a scrubbed concentrate;

[0008] S3. The scrubbed concentrate obtained in step S2 is subjected to magnetic separation to obtain a magnetic product and a non-magnetic product;

[0009] S4. Reverse flotation is performed on the magnetic product obtained in step S3 to remove impurities to obtain a coarse concentrate and black impurities;

[0010] S5. The rough concentrate obtained in step S4 is subjected to one positive flotation roughing and five positive flotation concentrating to obtain a flotation concentrate and a middling;

[0011] S6. The flotation concentrate obtained in step S5 is subjected to reduction leaching to obtain a concentrate product and a leachate; the obtained concentrate product is used as the refined calcite powder.

[0012] Furthermore, in step S1, the crushing is a three-stage closed-circuit crushing, and the particle size of the product obtained by crushing is 0.5-0.8 mm.

[0013] The grinding is dry ball milling, the volume ratio of material to grinding medium is 1:1, the total volume of the grinding system accounts for 2 / 3 of the ball mill solvent, the grinding time is 40-45 minutes, and the grinding until the material particle size reaches -0.074mm accounts for more than 98%.

[0014] According to the structural characteristics of limestone ore and the basic principles of crushing and grinding, the embedded particle size of calcite and gangue minerals is relatively fine. Only after a long period of crushing and grinding can the original ore be separated from the gangue minerals. This will improve the selective adsorption of subsequent flotation agents. Grinding the original ore finely is beneficial to increase the reaction sites and facilitate the efficient reduction leaching.

[0015] Furthermore, in step S2, the scrubbing process conditions are: adding 200-300 g / t of oxalic acid for scrubbing, the scrubbing concentration is 25-30%, the scrubbing time is 10 min, and the scrubbing speed is 1000-1200 rpm / min.

[0016] Scrubbing exposes fresh mineral interfaces, thereby improving the interaction between subsequent flotation reagents and minerals.

[0017] Furthermore, in step S3, the process conditions of magnetic separation are: pulp concentration of 25% to 30%, magnetic field strength of 12000 Gs to 14000 Gs, and magnetic separation is performed twice.

[0018] The original ore contains some magnetic iron. The iron impurities can be preferentially enriched through strong magnetic field and high gradient magnetic separation. The efficiency of magnetic separation is high and the loss of original ore is small.

[0019] Further, in step S4, the reverse flotation impurity removal includes two stages of reverse flotation, namely, roughing and scavenging, wherein the reverse flotation roughing obtains roughing concentrate and roughing tailings, and the reverse flotation scavenging uses the roughing concentrate as the flotation raw material to obtain the roughing concentrate and scavenging tailings; the roughing tailings and the scavenging tailings are combined to obtain black impurities;

[0020] The process conditions of reverse flotation roughing are: pulp concentration of 20% to 30%, pH value range of 8.5 to 9.5, collector is benzohydroxamic acid, the amount of collector is 50-75g / t, frother is pinene alcohol, the amount of frother is 50-75g / t;

[0021] The process conditions for reverse flotation scavenging are: pulp concentration of 20% to 30%, pH value range of 8.5 to 9.5, collector is benzohydroxamic acid, the amount of collector is 25-30g / t, frother is pinene alcohol, the amount of frother is 25-30g / t.

[0022] Further, in step S5, the one positive flotation roughing and five positive flotation cleaning are specifically as follows: the pulp concentration of the positive flotation roughing and positive flotation cleaning is 25% to 30%, and the pH value range is 8.5 to 9.5; the inhibitor of the positive flotation roughing is a combination of caustic starch and water glass, wherein the amount of caustic starch is 400 to 600 g / t, the amount of water glass is 400 to 600 g / t, and the collector is sodium oleate, and the amount is 250 to 350 g / t;

[0023] The inhibitor of the first and second stage positive flotation is a combination of caustic starch and water glass, wherein the dosage of caustic starch is 400-600g / t, and the dosage of water glass is 400-600g / t; the collector is sodium oleate, and the dosage is 100-200g / t;

[0024] The inhibitor of the third stage of positive flotation is a combination of caustic starch and water glass, wherein the dosage of caustic starch is 400-600g / t, the dosage of water glass is 400-600g / t; the collector is sodium oleate, the dosage is 50-100g / t;

[0025] The depressant in the fourth stage of positive flotation is a combination of caustic starch and water glass, wherein the amount of caustic starch is 400-600g / t, and the amount of water glass is 400-600g / t; no collector is added;

[0026] The fifth stage of positive flotation selection is blank selection.

[0027] The preparation method of the caustic starch is specifically as follows: corn starch and sodium hydroxide powder are mixed, water is added, and the mixture is heated in a water bath for a preset time to obtain the caustic starch;

[0028] The ratio of corn starch, sodium hydroxide powder and water is (1-2): (0.3-0.5): (17-18); the water bath heating temperature is 80-85° C., and the heating time is 1-1.5 hours.

[0029] The main components of the gangue minerals of limestone ore are quartz and dolomite, among which the impurity iron component mainly exists in the form of silicate, and the impurity magnesium component mainly exists in the form of dolomite. Calcite has a natural hydrophobic structure and has good floatability. Quartz and silicate minerals are hydrophilic and have poor floatability. Therefore, the difference in floatability between the two can be used to effectively separate the two through flotation.

[0030] Furthermore, in step S6, the reduction leaching is specifically as follows: the flotation concentrate obtained in step S5 is prepared into a 18-22% solution, a reduction leaching agent and sodium hydroxide powder are added, and heating reaction leaching is performed to obtain a reduction leaching concentrate and a leachate;

[0031] The reducing leaching agent is thiourea dioxide, and the dosage is 1% to 5% of the flotation concentrate obtained by the fifth positive flotation selection; the addition amount of sodium hydroxide powder is 0.3% to 0.5%; the heating temperature is 60 to 70°C, and the leaching time is 18 to 22 minutes; the reducing leaching agent is added to the reaction system in five times after the heating starts, and the interval time is 1 / 5 of the total leaching time.

[0032] The positive flotation concentrate produced in the process of positive flotation concentration has a high calcium carbonate content, but the impurity component content is too high to reach the lower middlings of refined calcite powder. This part of the middlings has a high yield and has not been effectively treated. The reduction leaching method can reduce this part of the trivalent iron, but the reduction reaction is reversible and this reaction needs to be carried out in a short time, so the reducing agent is added in stages to promote its leaching.

[0033] Principle of the present invention:

[0034] The synergistic use of benzohydroxamic acid and pine alcohol in the flotation of the present invention can achieve the separation of impurity minerals introduced by crushing and grinding in the actual production process, such as common impurity minerals with good floatability such as biotite. In addition, caustic starch is used as an inhibitor in the selection process. Anionic starch relies on electrostatic force to adsorb on the surface of positively charged hematite, or relies on hydrogen atoms on the hydroxyl groups of starch molecules to form hydrogen bonds with oxygen atoms on the surface of iron oxide lattices to form adsorption, thereby producing an inhibitory effect, and starch causticized with sodium hydroxide can be hydrolyzed into starch with a smaller molecular weight, which has stronger selectivity. Water glass can not only be used as an inhibitor, but also belongs to a dispersant for mineral mud. Through the synergistic inhibitory effect of the two inhibitors, the selectivity of the flotation collector sodium oleate can be greatly improved by taking advantage of their strengths and weaknesses.

[0035] Beneficial effects of the present invention:

[0036] (1) The present invention utilizes the difference in mineral floatability to achieve separation of fine particles through flotation;

[0037] (2) The method of the present invention uses caustic starch and water glass to act synergistically as inhibitors, thereby enhancing the inhibitory effect and selectivity and enhancing the separation between useful minerals and gangue minerals;

[0038] (3) The method of the present invention is for reduction leaching of flotation concentrate, which takes a short time and is simple to operate, thereby reducing the loss of concentrate yield and recovery rate of the original ore;

[0039] (4) The method of the present invention mixes the concentrated ore with the leached ore, thereby improving the recovery rate of the concentrate;

[0040] (5) The equipment used in the method of the present invention is conventional mineral processing equipment, the process flow is simple, and it is easy to industrialize and mass produce. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the process of Example 1 of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] The present invention discloses a method for preparing refined calcite powder by combining limestone ore dressing and smelting, and the schematic flow diagram thereof is as follows: Figure 1 As shown, specifically:

[0045] The limestone ore is crushed, and 200g of the crushed limestone ore is taken, wherein the quantitative CaO content of the original ore is 53.28%, the MgO content is 0.88%, the Fe2O3 content is 0.23%, and the SiO2 content is 1.60%. The ore is added into a ball mill for grinding (the ball mill is a planetary four-barrel grinder), and the material-ball ratio is adjusted to 1:1. The forward and reverse rotations are each 5 minutes as one cycle, and four cycles are performed in total. The total grinding time is 40 minutes, and the original ore is ground to 200 mesh (0.074mm) accounting for more than 98%, to obtain mineral powder.

[0046] The mineral powder is adjusted to a 25% concentration slurry, and slowly added to a 14000Gs high gradient magnetic separator for magnetic separation. The resulting magnetic concentrate is filtered and dried. Take 60g of magnetic concentrate for flotation (the flotation machine is a 200ml~300ml XFG hanging tank aerated flotation machine), adjust the slurry concentration to 20%, and use sodium carbonate to adjust the pH to 9 throughout the process. The reverse flotation impurity removal and roughing agent system is benzohydroxamic acid 50g / t, pine oil 50g / t, the reverse flotation impurity removal and sweeping agent system is benzohydroxamic acid 25g / t, pine oil 25g / t, the positive flotation roughing agent system is caustic starch 500g / t, water glass 500g / t, sodium oleate 300g / t, and the positive flotation roughing agent system is 100g / t. The reagent system of flotation selection 1 and 2 is caustic starch 500g / t, water glass 500g / t, sodium oleate 150g / t, the reagent system of positive flotation selection 3 is caustic starch 500g / t, water glass 500g / t, sodium oleate 75g / t, the reagent system of positive flotation selection 4 is caustic starch 500g / t, water glass 500g / t, positive flotation selection 5 is blank flotation, and the scraping time of each group is controlled to be 3min after foaming. Flotation concentrate and flotation ore are obtained respectively, and the flotation concentrate is subjected to reduction leaching. The reduction leaching conditions are 20% concentration pulp, 0.5% sodium hydroxide powder, 3% thiourea dioxide, 60℃ water bath heating, wherein thiourea dioxide is added in five times, each time with an interval of four minutes, for a total of 20 minutes. The reduction leaching concentrate obtained is the refined calcite powder product with a yield of 30.95%, wherein the CaO content is 54.05%, the Fe2O3 content is 0.045%, the MgO content is 0.43%, and the SiO2 content is 0.22%, which meets the requirements of the refined calcite powder product.

[0047] Example 2

[0048] The limestone ore is crushed, and 200g of the crushed limestone ore is taken, wherein the quantitative CaO content of the original ore is 53.28%, the MgO content is 0.88%, the Fe2O3 content is 0.23%, and the SiO2 content is 1.60%. The ore is added into a ball mill for grinding (the ball mill is a planetary four-barrel grinder), and the material-ball ratio is adjusted to 1:1. The forward and reverse rotations are each 5 minutes as one cycle, and four cycles are performed in total. The total grinding time is 40 minutes, and the original ore is ground to 200 mesh (0.074mm) accounting for more than 98%, to obtain mineral powder.

[0049] The mineral powder is adjusted to a 25% concentration slurry, and slowly added to a 14000Gs high gradient magnetic separator for magnetic separation. The resulting magnetic concentrate is filtered and dried. Take 60g of magnetic concentrate for flotation (the flotation machine is a 200ml~300ml XFG hanging tank aerated flotation machine), adjust the slurry concentration to 20%, and use sodium carbonate to adjust the pH to 9 throughout the process. The reverse flotation impurity removal and roughing agent system is benzohydroxamic acid 50g / t, pine oil 50g / t, the reverse flotation impurity removal and sweeping agent system is benzohydroxamic acid 25g / t, pine oil 25g / t, the positive flotation roughing agent system is caustic starch 500g / t, water glass 500g / t, sodium oleate 300g / t, and the positive flotation roughing agent system is 100g / t. The reagent system of flotation selection 1 and 2 is caustic starch 500g / t, water glass 500g / t, sodium oleate 150g / t, the reagent system of positive flotation selection 3 is caustic starch 500g / t, water glass 500g / t, sodium oleate 75g / t, the reagent system of positive flotation selection 4 is caustic starch 500g / t, water glass 500g / t, positive flotation selection 5 is blank flotation, and the scraping time of each group is controlled to be 3min after foaming. Flotation concentrate and flotation ore are obtained respectively, and the flotation concentrate is subjected to reduction leaching. The reduction leaching conditions are 20% concentration pulp, 0.5% sodium hydroxide powder, 1% thiourea dioxide, and 60℃ water bath heating, in which thiourea dioxide is added in five times, each time with an interval of four minutes, for a total of 20 minutes. The reduction leaching concentrate obtained is the refined calcite powder product with a yield of 31.46%, wherein the CaO content is 54.51%, the Fe2O3 content is 0.045%, the MgO content is 0.46%, and the SiO2 content is 0.21%, which meets the requirements of the refined calcite powder product.

[0050] Comparative Example 1

[0051] Compared with Example 1, except that the inhibitor caustic starch is replaced by corn starch, the remaining steps are exactly the same as Example 1. The yield of the obtained calcite powder product is 28.88%, and the Fe2O3 content is 0.066%, which does not meet the product technical requirements for the iron content of refined calcite powder.

[0052] Comparative Example 2

[0053] Compared with Example 1, except that the reduction inhibitor thiourea dioxide was replaced by sodium hydrosulfite, the remaining steps were exactly the same as Example 1. The yield of the obtained calcite powder product was 31.63%, and the Fe2O3 content was 0.076%, which did not meet the product technical requirements for the iron content of refined calcite powder.

[0054] Comparative Example 3

[0055] Compared with Example 1, except that the collector sodium oleate is replaced by oxidized paraffin soap, the remaining steps are exactly the same as Example 1. The yield of the obtained calcite powder product is 12.57%, and the Fe2O3 content is 0.317%, which does not meet the product technical requirements for the iron content of refined calcite powder.

[0056] Comparative Example 4

[0057] Compared with Example 1, the overall flotation process is changed to reverse flotation, that is, the impurity gangue minerals are directly floated out to purify the calcite, and sodium hexametaphosphate is used as a dispersant and inhibitor, with an amount of 500g / t; benzohydroxamic acid is used as a collector, with an amount of 100g / t; pineneol is used as a frother, with an amount of 100g / t; and the scavenging is performed four times in total. The yield of the obtained calcite powder product is 77.70%, the CaO content is 53.22%, the Fe2O3 content is 0.171%, and the CaO content is even lower than that of the original ore. It does not meet the product technical requirements for the iron content of refined calcite powder.

[0058] It can be seen from the results of the above embodiments and comparative examples that the present invention, based on the flotation optimization reagent system, adopts a technical solution of combined beneficiation and smelting for synergistic impurity removal, which overcomes the problems of poor recovery effect and low degree of refinement of existing limestone ore impurity removal technologies, and realizes the impurity removal of limestone ore to efficiently prepare refined calcite powder.

Claims

1. A method for preparing refined calcite powder by limestone ore dressing and smelting, characterized in that: The following steps are involved: S1. Crushing and grinding the limestone ore to obtain mineral powder; S2. The mineral powder obtained in step S1 is scrubbed to obtain a scrubbed concentrate; S3. The scrubbed concentrate obtained in step S2 is subjected to magnetic separation to obtain a magnetic product and a non-magnetic product; S4. Reverse flotation is performed on the magnetic product obtained in step S3 to remove impurities to obtain a coarse concentrate and black impurities; S5. The rough concentrate obtained in step S4 is subjected to one positive flotation roughing and five positive flotation concentrating to obtain a flotation concentrate and a middling; S6. The flotation concentrate obtained in step S5 is subjected to reduction leaching to obtain a concentrate product and a leachate; the obtained concentrate product is used as the refined calcite powder.

2. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 1, characterized in that: In step S1, the crushing is a three-stage closed-circuit crushing, and the particle size of the product obtained by crushing is 0.5-0.8 mm; The grinding is dry ball milling, the volume ratio of material to grinding medium is 1:1, the total volume of the grinding system accounts for 2 / 3 of the ball mill solvent, the grinding time is 40-45 minutes, and the grinding until the material particle size reaches -0.074mm accounts for more than 98%.

3. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 1, characterized in that: In step S2, the scrubbing process conditions are: adding 200-300 g / t of oxalic acid for scrubbing, the scrubbing concentration is 25-30%, the scrubbing time is 10 min, and the scrubbing speed is 1000-1200 rpm / min.

4. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 1, characterized in that: In step S3, the process conditions of magnetic separation are: pulp concentration of 25% to 30%, magnetic field strength of 12000 Gs to 14000 Gs, and magnetic separation is performed twice.

5. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 1, characterized in that: In step S4, the reverse flotation impurity removal includes two stages of reverse flotation, namely, roughing and scavenging, wherein the reverse flotation roughing obtains roughing concentrate and roughing tailings, and the reverse flotation scavenging uses the roughing concentrate as the flotation raw material to obtain the roughing concentrate and scavenging tailings; the roughing tailings and the scavenging tailings are combined to obtain black impurities; The process conditions of reverse flotation roughing are: pulp concentration of 20% to 30%, pH value range of 8.5 to 9.5, collector is benzohydroxamic acid, the amount of collector is 50-75g / t, frother is pinene alcohol, the amount of frother is 50-75g / t; The process conditions for reverse flotation scavenging are: pulp concentration of 20% to 30%, pH value range of 8.5 to 9.5, collector is benzohydroxamic acid, the amount of collector is 25-30g / t, frother is pinene alcohol, the amount of frother is 25-30g / t.

6. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 1, characterized in that: In step S5, the one-pass positive flotation roughing and five-pass positive flotation cleaning are specifically as follows: the pulp concentration of the positive flotation roughing and positive flotation cleaning is 25% to 30%, and the pH value range is 8.5 to 9.5; the inhibitor of the positive flotation roughing is a combination of caustic starch and water glass, wherein the amount of caustic starch is 400 to 600 g / t, the amount of water glass is 400 to 600 g / t, and the collector is sodium oleate, and the amount is 250 to 350 g / t; The inhibitor of the first and second stage positive flotation is a combination of caustic starch and water glass, wherein the dosage of caustic starch is 400-600g / t, and the dosage of water glass is 400-600g / t; the collector is sodium oleate, and the dosage is 100-200g / t; The inhibitor of the third stage of positive flotation is a combination of caustic starch and water glass, wherein the dosage of caustic starch is 400-600g / t, the dosage of water glass is 400-600g / t; the collector is sodium oleate, the dosage is 50-100g / t; The depressant in the fourth stage of positive flotation is a combination of caustic starch and water glass, wherein the amount of caustic starch is 400-600g / t, and the amount of water glass is 400-600g / t; no collector is added; The fifth stage of positive flotation selection is blank selection.

7. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 6, characterized in that: The preparation method of the caustic starch is specifically as follows: corn starch and sodium hydroxide powder are mixed, water is added, and the mixture is heated in a water bath for a preset time to obtain the caustic starch; The ratio of corn starch, sodium hydroxide powder and water is (1-2): (0.3-0.5): (17-18); the water bath heating temperature is 80-85° C., and the heating time is 1-1.5 hours.

8. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 1, characterized in that: In step S6, the reduction leaching is specifically as follows: the flotation concentrate obtained in step S5 is prepared into a 18-22% solution, a reduction leaching agent and sodium hydroxide powder are added, and heating reaction leaching is performed to obtain a reduction leaching concentrate and a leachate.

9. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 8, characterized in that: The reducing leaching agent is thiourea dioxide, and the dosage is 1% to 5% of the flotation concentrate obtained by the fifth positive flotation selection; the addition amount of sodium hydroxide powder is 0.3% to 0.5%; the heating temperature is 60 to 70°C, and the leaching time is 18 to 22 minutes.

10. The method for preparing refined calcite powder by limestone ore dressing and smelting according to claim 8, characterized in that: The reducing leaching agent is added to the reaction system in five times after the heating starts, and the interval time is 1 / 5 of the total leaching time.

Images