Combined inhibitor for reverse flotation magnesium removal of sedimentary phosphorite and method thereof

Abstract

The invention relates to the technical field of mineral separation technologies, in particular to a combined inhibitor and method for reverse flotation magnesium removal of sedimentary phosphorite, and the combined inhibitor is prepared by compounding the following components in parts by mass: 20-30 parts of aluminum sulfate octadecahydrate, 50-70 parts of tartaric acid and 10-20 parts of citric acid. The method is completed through a technical route of coupling regulation and inhibition of apatite by a combined inhibitor and reinforced separation of calcium and magnesium carbonate minerals by a mixed collecting agent. The method comprises the following steps: removing magnesium through a'one-roughing, one-refining and one-sweeping 'process under the condition that the pH value is 6-7 by combining with a sodium oleate / dodecylbenzene sulfonic acid / 2-ethylhexyl phosphate 2-ethylhexyl ester mixed collecting agent, so as to obtain phosphate concentrate with MgO less than 0.8%, P2O5 more than 29% and recovery rate more than 90%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mineral processing, in particular to a combined depressant for reverse flotation of magnesium from sedimentary phosphate ore and a method thereof. BACKGROUND

[0002] Phosphate rock is a raw material for producing phosphate fertilizer and phosphate, which is a non-renewable inorganic mineral resource, widely used in agriculture, food, medicine, battery materials and other fields, and plays an important role in the national economy and social development. China's total phosphate resources are rich, ranking second in the world, but most of them are medium and low grade phosphate ores. With the continuous exploitation and utilization of phosphate resources, the properties of the ores are gradually approaching to be poor, fine and impure, and it is urgent to develop and utilize phosphate ores reasonably.

[0003] Sedimentary phosphorite deposits are the main phosphate deposits in China. Sedimentary phosphate ores are often associated with a large amount of calcium-magnesium carbonate gangue minerals such as dolomite and calcite. At present, flotation is one of the most commonly used methods for phosphate ore dressing. Because the surface properties of apatite and calcium-magnesium carbonate minerals are similar, and the floatability is similar, calcium-magnesium carbonate minerals, especially dolomite, are easily introduced into the phosphate concentrate, causing the MgO content in the concentrate to exceed the standard, increasing the subsequent production cost.

[0004] There are many research reports on the separation of sedimentary phosphate resources. In the process of reverse flotation of magnesium, sulfuric acid and phosphoric acid are often used to adjust the slurry to strong acidity, and then to inhibit apatite, and fatty acid is used to collect calcium-magnesium carbonate minerals. In this process, there are problems such as high acid consumption, poor environment in the flotation workshop, poor performance of fatty acid collectors, high viscosity of flotation foam, and easy tailing of apatite. For example, Chinese patent document CN105597939A discloses a "low-grade siliceous calcareous collophanite beneficiation process", in which the pH value is adjusted to 4-6 by sulfuric acid for reverse flotation roughing, and phosphoric acid is used as a depressant, and butter is used as a collector for roughing. The pH value is adjusted to 3.5-3.9 by sulfuric acid for reverse flotation scavenging. In addition, Chinese patent document CN110369152A discloses a "micro-fine particle phosphate ore flotation process", in which the pH value of the desilicated concentrate slurry is adjusted to 5.3-5.6 by phosphoric acid, and the desilicated concentrate slurry is floated by using fatty acid soap collector XF-1. The above-mentioned reports still have the common problems of high acid consumption and poor selectivity of the collector under acidic conditions.

[0005] To achieve effective separation of apatite and dolomite, members of the field have studied dolomite inhibitors and proposed methods for magnesium removal by positive flotation, such as Chinese patent document CN118594775A discloses "a dolomite inhibitor and its application method", which uses sodium salt of dextran sulfate to inhibit dolomite, and uses fatty acid collectors to separate apatite. However, this method is limited to the separation of artificial mixed ores, and its applicability to actual phosphate ores needs to be verified. Based on the above status, the process and technology of reverse flotation magnesium removal of sedimentary phosphate rock need to be improved. SUMMARY

[0006] The purpose of the present application is to provide a combined inhibitor for reverse flotation magnesium removal of sedimentary phosphate rock and a method thereof. The present application is completed by the technical route of "combined inhibitor coupled regulation and control of apatite inhibition-mixed collector strengthened separation of calcium and magnesium carbonate minerals". The sodium oleate / dodecylbenzenesulfonic acid / 2-ethylhexyl 2-ethylhexyl phosphate mixed collector is used to remove magnesium by "one roughing, one cleaning and one scavenging" process at pH 6-7, and a phosphate concentrate with MgO <0.8%, P2O5>29% and recovery >90% is obtained.

[0007] To achieve the above technical purpose and achieve the above technical effect, the present application is realized by the following technical scheme: A combined inhibitor for reverse flotation magnesium removal of sedimentary phosphate rock is prepared by compounding the following components in mass fraction: aluminum sulfate octadecahydrate 20-30 parts, tartaric acid 50-70 parts and citric acid 10-20 parts.

[0008] On the other hand, the present application proposes a method for reverse flotation magnesium removal of sedimentary phosphate rock based on the above-mentioned combined inhibitor, comprising the following steps: S1: grinding the sedimentary phosphate rock, the grinding pulp concentration is 60-70%, and the fine material fineness is 80-85% of -0.074 mm; S2: sequentially adding the combined inhibitor and the mixed collector to the fine material obtained in S1, with a dosing interval of 2-4 min, stirring for 2-4 min, and then air flotation for 3-4 min to perform roughing magnesium removal, to obtain a roughing concentrate and a roughing tailing; S3: sequentially adding the combined inhibitor and the mixed collector to the roughing concentrate obtained in S2, with a dosing interval of 2-4 min, stirring for 2-4 min, and then air flotation for 2-3 min to perform cleaning magnesium removal, to obtain a phosphate concentrate and a cleaning tailing; S4: adding the combined inhibitor to the roughing tailing obtained in S2, stirring for 2-4 min, and then air flotation for 3-4 min to perform scavenging magnesium removal, to obtain a scavenging concentrate and a tailing; Wherein, the scavenging concentrate and the cleaning tailing are combined and returned to the roughing magnesium removal operation; Furthermore, the combined inhibitor is composed of the following components in parts by weight: 20-30 parts aluminum sulfate octahydrate, 50-70 parts tartaric acid, and 10-20 parts citric acid; Furthermore, the mixed collector is composed of the following components in parts by weight: 40-60 parts sodium oleate, 20-30 parts dodecylbenzenesulfonic acid, and 20-30 parts 2-ethylhexyl phosphate 2-ethylhexyl ester.

[0009] Furthermore, based on the raw ore, the dosage of the combined inhibitor in step S2 is 1.5–3 kg / t, and the pH value of the slurry is 6–7; the dosage of the combined inhibitor in step S3 is 0.5–1 kg / t; and the dosage of the combined inhibitor in step S4 is 0.8–1.5 kg / t.

[0010] Furthermore, based on the raw ore, the amount of mixed collector used in step S2 is 800–1200 g / t; and the amount of mixed collector used in step S3 is 400–600 g / t.

[0011] Furthermore, the sedimentary phosphate rock has a P2O5 grade of ≥20% and an MgO content of 5-8%.

[0012] The combined inhibitor inhibits apatite through the following mechanism: Al(III) generated from the hydrolysis of aluminum sulfate octahydrate reacts with PO4 on the surface of apatite. 3- The oxygen atoms in the atom undergo a chemical reaction to form aluminum hydroxyl (Al(OH)4). - This enhances the steric hindrance and electrostatic repulsion of the apatite surface; The carboxyl and hydroxyl functional groups of tartaric acid and citric acid adsorb onto the Ca sites on the apatite surface, and enhance the hydrophilicity of the apatite surface through hydrogen bonding between the F sites and the functional groups.

[0013] The beneficial effects of this invention are: In existing technologies, reverse flotation demagnesification processes often use sulfuric acid, phosphoric acid, and their mixtures as inhibitors for apatite, and fatty acids as collectors for calcium magnesium carbonate gangue minerals. The flotation pulp is strongly acidic, resulting in high acid consumption and insufficient separation performance of the collectors. In contrast, this invention uses a compound of aluminum sulfate octadecyl hydrate, tartaric acid, and citric acid as a combined inhibitor, which effectively inhibits apatite in near-neutral pulp conditions (pH 6-7) and improves the separation performance of subsequent mixed collectors.

[0014] The combined inhibitor used in this invention achieves selective inhibition of apatite through a "metal ion modification-organic small molecule coupling modification" technique.

[0015] In the combined inhibitor of this invention, Al (= 3 * ROMAN * MERGEFORMAT III) from the hydrolysis of aluminum sulfate octahydrate reacts with PO4 on the surface of apatite. 3- The O atoms in the solution undergo chemical reactions, and after modification with Al ions, hydrophilic aluminum hydroxyl (Al(OH)4) is generated. - The combined inhibitors enhance the steric hindrance and electrostatic repulsion on the apatite surface, thus hindering the adsorption of subsequent collectors. Simultaneously, the functional groups (-COOH and -OH) in the tartaric acid and citric acid organic molecules preferentially adsorb onto the Ca sites on the apatite surface, enhancing the hydrophilicity of the mineral surface. Furthermore, hydrogen bonding occurs between the F sites on the apatite surface and the functional groups of tartaric acid and citric acid, further enhancing the hydrophilicity of the apatite surface. Therefore, the coupled modification effect of the combined inhibitors effectively suppresses apatite, creating favorable conditions for reverse flotation magnesium removal and phosphorus extraction.

[0016] The combined inhibitor of this invention is environmentally friendly and pollution-free, and its application method is simple and easy for industrial production. The mixed collector of this invention, through synergistic effects, can significantly reduce the surface tension of the solution and promote the interaction between the collector and the surface of calcium magnesium carbonate gangue minerals, achieving excellent demagnesiation and phosphorus extraction effects. This invention does not involve the addition of phosphoric acid or sulfuric acid, and the resulting phosphate concentrate has an MgO content of less than 0.8%, a P2O5 grade of greater than 29%, and a recovery rate of greater than 90%.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The application of a combined depressant for deposit type phosphate ore reverse flotation magnesium removal, comprising: grinding the raw ore, and using the process of "one roughing, one scavenging and one cleaning" to realize the effective removal of magnesium in the phosphate ore. The combined depressant and mixed collector are added in the roughing and scavenging operations, and the combined depressant is added in the scavenging operation; specifically comprising the following steps: S1: grinding the deposit type phosphate ore to obtain fine material. The pulp concentration of the grinding is 60-70%, and the fineness of the fine material is 80-85% of -0.074 mm; S2: adding the combined depressant and the mixed collector to the fine material obtained in step S1 in sequence, the dosing interval is 2-4 min, stirring for 2-4 min, and then aerofloat for 3-4 min to carry out magnesium removal roughing to obtain roughing concentrate (in-tank product) and roughing tailings (foam product); S3: adding the combined depressant and the mixed collector to the roughing concentrate obtained in step S2 in sequence, the dosing interval is 2-4 min, stirring for 2-4 min, and then aerofloat for 2-3 min to carry out magnesium removal cleaning to obtain phosphate concentrate (in-tank product) and cleaning tailings (foam product); S4: adding the combined depressant to the roughing tailings obtained in step S2, stirring for 2-4 min, and then aerofloat for 3-4 min to carry out magnesium removal scavenging to obtain scavenging concentrate (in-tank product) and tailings (foam product). The scavenging concentrate and the cleaning tailings obtained in step S3 are combined and returned to the magnesium removal roughing.

[0022] In step S1, the deposit type phosphate ore is characterized in that the P2O5 grade of the raw ore is greater than 20%, and the MgO content is 5-8%.

[0023] In steps S2-4, the combined depressant is a complex of aluminum sulfate octadecahydrate, tartaric acid and citric acid, wherein the aluminum sulfate octadecahydrate is 20-30 parts, the tartaric acid is 50-70 parts, and the citric acid is 10-20 parts; the mixed collector is a complex of sodium oleate, dodecyl benzene sulfonic acid and 2-ethylhexyl phosphonic acid 2-ethylhexyl ester, wherein the sodium oleate is 40-60 parts, the dodecyl benzene sulfonic acid is 20-30 parts, and the 2-ethylhexyl phosphonic acid 2-ethylhexyl ester is 20-30 parts.

[0024] In steps S2-4, the dosage of the combined depressant (based on the raw ore) is 1.5-3 Kg / t (roughing, pulp pH 6-7), 0.5-1 Kg / t (cleaning) and 0.8-1.5 Kg / t (scavenging).

[0025] In steps S2-3, the dosage of the mixed collector (based on the raw ore) is 800-1200 g / t (roughing) and 400-600 g / t (cleaning).

[0026] Example 1 A certain sedimentary phosphate rock has a P2O5 grade of 20.75% and a MgO content of 5.3%. The main minerals in the raw ore are fluorapatite, dolomite and quartz; in addition, there are small amounts of microcline, calcite and pyrite, P2O5 exists in the form of fluorapatite, MgO exists in the form of dolomite, and SiO2 exists in the form of quartz and microcline.

[0027] A combined depressant for reverse flotation of magnesium from sedimentary phosphate rock and its application, comprising the following steps: S1: grinding the sedimentary phosphate rock to obtain fine particles. The pulp concentration of grinding is 60%, and the fineness of fine particles is 80.5% of -0.074 mm; S2: adding the combined depressant 1.5 Kg / t (wherein, aluminum sulfate octadecahydrate is 20 parts, tartaric acid is 70 parts, and citric acid is 10 parts, and the pulp pH is 6.5) and the mixed collector 800 g / t (wherein, sodium oleate is 40 parts, dodecylbenzenesulfonic acid is 30 parts, and 2-ethylhexyl 2-ethylhexyl phosphonate is 30 parts) to the fine particles obtained in step S1 in turn, with a dosing interval of 2 min, stirring for 2 min, and then air flotation for 3 min to perform roughing of magnesium removal, to obtain roughing concentrate (in-tank product) and roughing tailings (foam product); S3: adding the combined depressant 0.5 Kg / t (wherein, aluminum sulfate octadecahydrate is 20 parts, tartaric acid is 70 parts, and citric acid is 10 parts) and the mixed collector 400 g / t (wherein, sodium oleate is 40 parts, dodecylbenzenesulfonic acid is 30 parts, and 2-ethylhexyl 2-ethylhexyl phosphonate is 30 parts) to the roughing concentrate obtained in step S2 in turn, with a dosing interval of 2 min, stirring for 2 min, and then air flotation for 2 min to perform cleaning of magnesium removal, to obtain phosphate concentrate (in-tank product) and cleaning tailings (foam product); S4: adding the combined depressant 0.8 Kg / t (wherein, aluminum sulfate octadecahydrate is 20 parts, tartaric acid is 70 parts, and citric acid is 10 parts) to the roughing tailings obtained in step S2, stirring for 2 min, and then air flotation for 3 min to perform scavenging of magnesium removal, to obtain scavenging concentrate (in-tank product) and tailings (foam product). The scavenging concentrate and the cleaning tailings obtained in step S3 are combined and returned to the roughing of magnesium removal. The test results show that the P2O5 grade of the phosphate concentrate is 29.26%, the recovery rate is 90.08%, and the MgO content is 0.85%.

[0028] Comparative Example 1 The other conditions are consistent with example 1, the difference is that the combined inhibitor does not add aluminum sulfate octadecahydrate, and the mass ratio of tartaric acid to citric acid is 7:1 instead of the same amount of aluminum sulfate octadecahydrate, the dosage of the combined inhibitor in each operation is unchanged, and the effect of tartaric acid and citric acid combination is analyzed. The test results show that the P2O5 grade of phosphate concentrate is 28.16%, the recovery rate is 88.45%, and the MgO content is 1.03%.

[0029] Comparative example 2 The other conditions are consistent with example 1, the difference is that the combined inhibitor does not add tartaric acid, and the mass ratio of aluminum sulfate octadecahydrate to citric acid is 2:1 instead of the same amount of tartaric acid, the dosage of the combined inhibitor in each operation is unchanged, and the effect of aluminum sulfate octadecahydrate and citric acid combination is analyzed. The test results show that the P2O5 grade of phosphate concentrate is 28.02%, the recovery rate is 88.04%, and the MgO content is 1.09%.

[0030] Comparative example 3 The other conditions are consistent with example 1, the difference is that the combined inhibitor does not add citric acid, and the mass ratio of aluminum sulfate octadecahydrate to tartaric acid is 2:7 instead of the same amount of citric acid, the dosage of the combined inhibitor in each operation is unchanged, and the effect of aluminum sulfate octadecahydrate and tartaric acid combination is analyzed. The test results show that the P2O5 grade of phosphate concentrate is 28.63%, the recovery rate is 89.12%, and the MgO content is 1.02%.

[0031] Example 2 The sedimentary phosphate rock used in this example has a P2O5 grade of 22.35%, a MgO content of 6.7%, a SiO2 content of 18.65%, and the main phosphorus-containing mineral is fluorapatite. The main magnesium carbonate gangue mineral is dolomite, and there are also a small amount of microcline and calcite.

[0032] A combined inhibitor for the reverse flotation of magnesium from sedimentary phosphate rock and its application, comprising the following steps: S1: grinding the sedimentary phosphate rock to obtain fine particles. The pulp concentration of grinding is 65%, and the fineness of fine particles is 83.6% of -0.074 mm; S2: adding the combined inhibitor 2.5 Kg / t (aluminum sulfate octadecahydrate 25 parts, tartaric acid 60 parts, citric acid 15 parts, pulp pH 6.2) and mixing collector 1000 g / t (sodium oleate 50 parts, dodecylbenzenesulfonic acid 25 parts, 2-ethylhexyl phosphonic acid 2-ethylhexyl ester 25 parts) to the fine particles obtained in step S1 in turn, with a dosing interval of 3 min, stirring for 3 min, and then air flotation for 4 min to carry out roughing, to obtain roughing concentrate (in-tank product) and roughing tailings (foam product); S3: To the rough concentrate obtained in step S2, a combined depressant 0.8 Kg / t (in which, aluminum sulfate octadecahydrate is 25 parts, tartaric acid is 60 parts, and citric acid is 15 parts) and a mixed collector 500 g / t (in which, sodium oleate is 50 parts, dodecyl benzene sulfonic acid is 25 parts, and 2-ethylhexyl phosphonic acid 2-ethylhexyl ester is 25 parts) are added in sequence, the dosing interval is 3 min, and after stirring for 3 min, flotation is carried out for 3 min under air inflation, to obtain a phosphorus concentrate (in-tank product) and a roughing tailing (foam product) by carrying out a magnesium removal roughing; S4: To the roughing tailing obtained in step S2, a combined depressant 1.2 Kg / t (in which, aluminum sulfate octadecahydrate is 25 parts, tartaric acid is 60 parts, and citric acid is 15 parts) is added, and after stirring for 3 min, flotation is carried out for 4 min under air inflation, to obtain a cleaning concentrate (in-tank product) and a tailing (foam product) by carrying out a magnesium removal cleaning. The cleaning concentrate and the cleaning tailing obtained in step S3 are combined and returned to the magnesium removal roughing. The test results show that a phosphorus concentrate with a P2O5 grade of 30.43% and a recovery rate of 92.15% is obtained, and the MgO content is 0.88%.

[0033] Comparative Example 4 The other conditions are consistent with those in Example 2, except that the combined depressant is replaced by sulfuric acid, and the amount of sulfuric acid used in each operation is 1.5 times that of the combined depressant. The test results show that a phosphorus concentrate with a P2O5 grade of 30.55% and a recovery rate of 92.05% is obtained, and the MgO content is 0.82%.

[0034] Comparative Example 5 The other conditions are consistent with those in Example 2, except that the combined depressant is replaced by sulfuric acid, and the amount of sulfuric acid used in each operation is 1.5 times that of the combined depressant. The test results show that a phosphorus concentrate with a P2O5 grade of 30.55% and a recovery rate of 92.05% is obtained, and the MgO content is 0.82%.

[0035] Comparative Example 6 The other conditions are consistent with those in Example 2, except that the combined depressant is replaced by phosphoric acid, and the amount of phosphoric acid used in each operation is the same as that of the combined depressant. The test results show that a phosphorus concentrate with a P2O5 grade of 29.13% and a recovery rate of 88.46% is obtained, and the MgO content is 1.15%.

[0036] Comparative Example 7 The other conditions are consistent with those in Example 2, except that the combined depressant is replaced by phosphoric acid, and the amount of phosphoric acid used in each operation is 1.5 times that of the combined depressant. The test results show that a phosphorus concentrate with a P2O5 grade of 30.75% and a recovery rate of 92.64% is obtained, and the MgO content is 0.85%.

[0037] Example 3 A sedimentary phosphate rock in Yunnan has a P2O5 grade of 21.68%, a MgO content of 7.8%, and a SiO2 content of 19.21%. P2O5 exists in the form of fluorapatite, MgO exists in the form of dolomite, and SiO2 exists in the form of quartz and microcline.

[0038] A combined depressant for reverse flotation of magnesium from a sedimentary phosphate rock and its application, comprising the following steps: S1: grinding the sedimentary phosphate rock to obtain fine particles. The pulp concentration of grinding is 70%, and the fineness of fine particles is 85% of -0.074 mm; S2: adding a combined depressant 3 Kg / t (wherein aluminum sulfate octadecahydrate is 30 parts, tartaric acid is 50 parts, and citric acid is 20 parts) and mixed collector 1200 g / t (wherein sodium oleate is 60 parts, dodecyl benzene sulfonic acid is 20 parts, and 2-ethylhexyl 2-ethylhexyl phosphonate is 20 parts) to the fine particles obtained in step S1 in turn, with a dosing interval of 4 min, stirring for 4 min, and then air flotation for 4 min to perform roughing of magnesium removal, to obtain roughing concentrate (in-tank product) and roughing tailings (foam product); S3: adding a combined depressant 1 Kg / t (wherein aluminum sulfate octadecahydrate is 30 parts, tartaric acid is 50 parts, and citric acid is 20 parts) and mixed collector 600 g / t (wherein sodium oleate is 60 parts, dodecyl benzene sulfonic acid is 20 parts, and 2-ethylhexyl 2-ethylhexyl phosphonate is 20 parts) to the roughing concentrate obtained in step S2 in turn, with a dosing interval of 4 min, stirring for 4 min, and then air flotation for 3 min to perform cleaning of magnesium removal, to obtain phosphate concentrate (in-tank product) and cleaning tailings (foam product); S4: adding a combined depressant 1.5 Kg / t (wherein aluminum sulfate octadecahydrate is 30 parts, tartaric acid is 50 parts, and citric acid is 20 parts) to the roughing tailings obtained in step S2, stirring for 4 min, and then air flotation for 4 min to perform scavenging of magnesium removal, to obtain scavenging concentrate (in-tank product) and tailings (foam product). The scavenging concentrate and cleaning tailings obtained in step S3 are combined and returned to roughing of magnesium removal. The test results show that the P2O5 grade of the phosphate concentrate is 30.28%, the recovery rate is 92.03%, and the MgO content is 0.81%.

[0039] Comparative Example 8 The other conditions are the same as in Example 3, except that sulfuric acid is used instead of the combined depressant, the amount of depressant used in each operation is unchanged, and sodium oleate is used instead of the mixed collector, and the amount of collector used in each operation is unchanged. The test results show that the P2O5 grade of the phosphate concentrate is 28.15%, the recovery rate is 88.91%, and the MgO content is 1.23%.

[0040] Comparative Example 9 The other conditions are consistent with Example 3, except that phosphoric acid is used instead of the combined depressant, the depressant dosage is unchanged in each operation, sodium oleate is used instead of the mixed collector, and the collector dosage is unchanged in each operation. The test results show that the P2O5 grade of the phosphate concentrate is 29.23%, the recovery rate is 89.12%, and the MgO content is 1.15%.

[0041] As can be seen from the above, the combination of aluminum sulfate octadecahydrate, tartaric acid and citric acid can effectively depress apatite under near-neutral pulp, thereby improving the separation effect of the combination of sodium oleate, dodecylbenzenesulfonic acid and 2-ethylhexyl 2-ethylhexyl phosphonate on calcium-magnesium carbonate gangue minerals. The results of Example 1 and Comparative Examples 1-3 show that the combination of aluminum sulfate octadecahydrate, tartaric acid and citric acid has a positive synergistic effect on the depression of apatite. Compared with the combined depressant of the present application, when any one of the depressant components is added less, the P2O5 grade and recovery rate of the phosphate concentrate decrease by 1-2 percentage points, and the MgO content is greater than 1%. The results of Example 2 and Comparative Examples 4-7 show that compared with sulfuric acid and phosphoric acid, the combined depressant of the present application can effectively depress apatite at a lower reagent dosage, and the effect of demagnesia and phosphorus extraction is more obvious. The results of Example 3 and Comparative Examples 8-9 show that under the same conditions, the conventional process using sulfuric acid and phosphoric acid as depressants and sodium oleate as collector cannot effectively demagnesia and phosphorus extraction of phosphate ore, and the MgO content in the phosphate concentrate is greater than 1%. Compared with this, the combined depressant and the mixed collector of the present application can obtain a phosphate concentrate with an MgO content of 0.81%, and the P2O5 grade and recovery rate of the phosphate concentrate are increased by 1-2%, realizing the reverse flotation demagnesia of sedimentary phosphate rock.

[0042] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The preferred embodiments do not describe all the details, nor limit the present application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present application. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and their full scope and equivalents.

Claims

1. A combined demagnesium inhibitor for reverse flotation demagnesiation of sedimentary phosphate rock, characterized in that, It is a compound of the following components in parts by weight: 20-30 parts aluminum sulfate octahydrate, 50-70 parts tartaric acid and 10-20 parts citric acid.

2. A method for demagnesification of sedimentary phosphate rock by reverse flotation based on the combined inhibitors described in claim 1, characterized in that: Includes the following steps: S1: Grinding of sedimentary phosphate rock to a pulp concentration of 60-70% yields fine-grained material with a fineness of -0.074 mm accounting for 80%-85%; S2: Add the combined inhibitor and the mixed collector to the fine-grained material obtained in S1 in sequence, with an interval of 2 to 4 minutes between additions. After stirring for 2 to 4 minutes, perform air flotation for 3 to 4 minutes to remove magnesium and roughing to obtain roughing concentrate and roughing tailings. S3: Add the combined inhibitor and mixed collector to the rough concentrate obtained in S2 in sequence, with an interval of 2-4 min between additions. Stir for 2-4 min and then perform aeration flotation for 2-3 min to remove magnesium and clean up the phosphate concentrate and cleaned tailings. S4: Add combined depressant to the roughing tailings obtained in S2, stir for 2-4 min, then aerate and float for 3-4 min to remove magnesium and scavenging, and obtain scavenging concentrate and tailings; The scavenged concentrate and the fined tailings are combined and returned to the magnesium removal roughing operation.

3. The method for demagnesification of sedimentary phosphate rock by reverse flotation as described in claim 2, characterized in that: The mixed collector is composed of the following components in parts by weight: 40-60 parts sodium oleate, 20-30 parts dodecylbenzenesulfonic acid, and 20-30 parts 2-ethylhexyl phosphate.

4. The method for demagnesification of sedimentary phosphate rock by reverse flotation as described in claim 2, characterized in that: Based on the raw ore, the dosage of the combined inhibitor in step S2 is 1.5–3 kg / t, and the pH value of the slurry is 6–7; the dosage of the combined inhibitor in step S3 is 0.5–1 kg / t; and the dosage of the combined inhibitor in step S4 is 0.8–1.5 kg / t.

5. The method for demagnesification of sedimentary phosphate rock by reverse flotation as described in claim 2, characterized in that: Based on the raw ore, the amount of mixed collector used in step S2 is 800-1200 g / t; the amount of mixed collector used in step S3 is 400-600 g / t.

6. The method for demagnesification of sedimentary phosphate rock by reverse flotation as described in claim 2, characterized in that: The sedimentary phosphate rock has a P2O5 grade of ≥20% and an MgO content of 5-8%.

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