Sorting process for synchronously removing silicon, magnesium and sesquioxide impurities from phosphorite

Abstract

The invention discloses a grading process for synchronously removing silicon, magnesium and sesquioxide impurities from phosphorite, and belongs to the technical field of mineral processing, after the phosphorite is ground, under the condition of alkalescence ore pulp (pH 8-9), sodium carbonate is added as a pH regulator, a combined inhibitor, a collecting agent N-dodecyl amino malonate and an auxiliary agent, and then the phosphorite is subjected to separation and purification to obtain the silicon-magnesium-sesquioxide impurity-removed phosphorite. The direct flotation process of roughing, refining and sweeping is adopted, and efficient separation of apatite and impurities such as dolomite, calcite, quartz and sesquioxide is achieved. The process is simple, the reagent cost is low, equipment corrosion can be remarkably relieved, high-quality phosphate concentrate with the P2O5 grade larger than or equal to 30%, MgO smaller than or equal to 1.0% and R2O3 smaller than or equal to 2.0% is obtained, the P2O5 recovery rate is high, meanwhile, tail water is easy to treat and reuse, and the novel collophanite beneficiation technology is efficient, economical and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of non-metallic ore dressing, and particularly relates to a beneficiation process for simultaneously removing silicon-magnesium and sesquioxide impurities from phosphate ores. BACKGROUND

[0002] Phosphate rock, as a non-renewable strategic chemical mineral resource, plays a crucial role in ensuring food security and stable national economy. At present, the global phosphate rock reserves are about 72 billion tons, which are unevenly distributed. With years of continuous exploitation, high-grade phosphate rock resources are becoming increasingly exhausted, and the efficient development and utilization of low-grade phosphate rock has become a breakthrough point in the field of mineral resources. At the same time, China, as the world's largest producer of phosphate rock and phosphate chemicals, currently has more than 70% of the domestic phosphate rock as sedimentary collophanite, which generally contains 15% to 25% of SiO2, 2% to 5% of MgO, and 3% to 8% of sesquioxide. The content of silicon-magnesium and sesquioxide is high. At present, the treatment of such ores is mainly based on "double reverse flotation": first, sulfuric acid is added to adjust the pH to 5 to 6 for magnesium removal by reverse flotation, and then amine collector is added to adjust the pH to 9 to 10 for silicon removal by reverse flotation. The process is long, and the repeated addition of acid and alkali not only increases the consumption of sulfuric acid, but also increases the corrosion of equipment and the cost of tail water treatment. Moreover, the recycled water is difficult to be directly recycled due to the fluctuation of acidity. At the same time, the residual Fe 3+ / Al 3+ is easy to form phosphogypsum scaling in phosphoric acid concentration operation, reducing the water solubility of subsequent fertilizers.

[0003] Therefore, under the background of tight global phosphate rock supply and continuously high prices, domestic phosphate rock is rapidly approaching the inflection point from "supply exceeding demand" to "supply less than demand", and it is urgent to use "weak alkaline direct flotation" one-step upgrading process to simultaneously inhibit dolomite, calcite, quartz and sesquioxide under natural weak alkaline pH conditions, which not only eliminates the consumption of a large amount of acid and alkali, but also significantly improves the P2O5 recovery rate and the quality of phosphoric acid, thereby ensuring the national food security and the green and low-carbon operation of the phosphate chemical industry chain. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a beneficiation process for simultaneously removing silicon-magnesium and sesquioxide impurities from phosphate ores. The process removes dolomite, calcite, quartz and sesquioxide impurities by direct flotation under weak alkaline slurry conditions in one step, and finally obtains high-grade phosphate concentrate and tailings. The process is simple, the reagent cost is low, the equipment corrosion is significantly reduced, and high-quality phosphate concentrate with P2O5 grade ≥ 30%, MgO ≤ 1.0%, and R2O3 ≤ 2.0% is obtained, the P2O5 recovery rate is high, and the tail water is easy to treat and reuse. It is a new efficient, economical and environmentally friendly collophanite beneficiation technology.

[0005] To solve the above technical problems, the basic idea of the technical solution of the present application is:

[0006] A beneficiation process for simultaneously removing silicon-magnesium and sesquioxide impurities from phosphate ore, comprising the following steps:

[0007] S1, crushing and grinding the phosphate ore to -0.074 mm, and preparing a slurry;

[0008] S2, performing positive flotation under weak alkaline conditions, adding pH adjusting agent sodium carbonate to adjust the pH of the slurry to 8-9, then adding a combination of inhibitors, collector N-dodecyl amino malonate and additives, and then performing one roughing, one cleaning and one scavenging to simultaneously remove dolomite, calcite, quartz and sesquioxide impurities, obtaining cleaned concentrate, scavenged tailings, middlings from the cleaning operation and middlings from the scavenging operation returning to the roughing operation, and the cleaned concentrate being the phosphate concentrate.

[0009] Further, in S1, the P2O5 grade of the phosphate ore is 20%-30%, the SiO2 content is 12-25%, the MgO content is 3-5%, and the sesquioxide R2O3 content is 3.5-6%, R representing Fe and Al.

[0010] Further, in S1, the -0.074 mm particle size accounts for more than 75%, and the slurry concentration is 25%-35%.

[0011] Further, in S2, the combination of inhibitors is one or any combination of sodium hexametaphosphate, sodium lignosulfonate and sodium carboxymethyl starch; the collector is N-dodecyl amino malonate; and the additive is sodium dodecyl benzene sulfonate and / or fatty acid polyoxyethylene ether.

[0012] Further, in S2, the one roughing, one cleaning and one scavenging are specifically:

[0013] In the roughing operation, a pH adjusting agent is added to the slurry to adjust the pH, and then a combination of inhibitors, a collector and an additive are added;

[0014] In the cleaning operation, a combination of inhibitors is added to the rough concentrate obtained in the roughing operation for cleaning;

[0015] In the scavenging operation, a collector and an additive are added to the roughing tailings obtained in the roughing operation for scavenging.

[0016] Further, in S2, in the roughing operation, the amount of sodium carbonate is 600-1200 g / t, the amount of the combination of inhibitors is 800-1200 g / t, the amount of the collector is 400-800 g / t, and the amount of the additive is 100-400 g / t;

[0017] In the cleaning operation, the amount of the added combination of inhibitors is 200-600 g / t;

[0018] The dosage of the added collector is 200-500 g / t, and the dosage of the added additive is 20-70 g / t.

[0019] Compared with the prior art, the present application has the following beneficial effects.

[0020] The present application provides a novel, simple, efficient and environmentally friendly beneficiation process, which can effectively remove dolomite, calcite, quartz and sesquioxide impurities in the phosphorus mineral flotation enrichment process of the medium and low grade collophanite, and achieve the flotation index of P2O5 grade of phosphorus concentrate ≥30%, MgO ≤1.0%, and R2O3 ≤2.0%. The beneficiation process is simple, easy to operate, low in cost, and suitable for large-scale industrial popularization and application.

[0021] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are part of the present application, serve to provide a further understanding of the present application, and the schematic embodiments of the present application and their descriptions serve to explain the present application, but do not constitute an improper limitation on the present application. Obviously, the accompanying drawings in the following description are only some embodiments, and other drawings can be obtained by those skilled in the art without creative labor. In the drawings:

[0023] Fig. 1 is a process flow diagram of the present application.

[0024] Fig. 2 Figure (a) shows the effect of the dosage of the collector N-dodecylaminopropandioate on the floatability of the mineral (a) - without adding the depressant; (b) - adding the combined depressant.

[0025] It should be noted that these drawings and written descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments will be clearly and completely described below with reference to the drawings of the embodiments of the present application. The following embodiments are used to illustrate the present application, but not to limit the scope of the present application.

[0027] In combination with the accompanying Figs. 1-2 drawings, the beneficiation process for simultaneously removing silicon, magnesium and sesquioxide impurities from phosphorus ore according to the present application has the following steps:

[0028] S1: crushing and grinding the phosphate ore to a certain grinding fineness; wherein the proportion of the particle size of -0.074 mm is greater than 75%, and the pulp concentration is 25%-35%;

[0029] S2: removing gangue minerals by positive flotation:

[0030] The pH of the raw ore is adjusted to 8-9 by adding sodium carbonate as a pH regulator, and then a combined depressant, a collector and an additive are added, and then one roughing, one cleaning and one scavenging are carried out. The collector and the additive are added during scavenging, the combined depressant is added during cleaning, and the middlings of cleaning and scavenging are combined and then added to the positive flotation roughing process, so as to finally obtain high-quality phosphate concentrate and flotation tailings.

[0031] In S1, the P2O5 grade of the phosphate ore is 20%-30%, the SiO2 content is 12-25%, the MgO content is 3-5%, and the sesquioxide R2O3 content is 3.5-6% (R represents Fe and Al).

[0032] In S2, the combined depressant is at least one or more combinations of sodium hexametaphosphate, sodium lignosulfonate and sodium carboxymethyl starch; the collector is N-dodecylaminopropandioate; and the additive is a mixture of sodium dodecylbenzenesulfonate and fatty acid polyoxyethylene ether.

[0033] In S2, during roughing, the sodium carbonate is used in an amount of 600-1200 g / t, the combined depressant is used in an amount of 800-1200 g / t, the collector is used in an amount of 400-800 g / t, and the additive is used in an amount of 100-400 g / t. In the cleaning process, the combined depressant is additionally used in an amount of 200-600 g / t, the collector is additionally used in an amount of 200-500 g / t during scavenging, and the additive is used in an amount of 20-70 g / t.

[0034] The molecular structure of the collector N-dodecylaminopropandioate involved in the positive flotation process of the present application is shown in the following figure. As can be seen from the molecular structure formula, the functional groups of N-dodecylaminopropandioate are carboxyl (-COO - ) and amino (-NH3 + ).

[0035]

[0036] The effects of N-dodecylaminopropandioate on the flotation behaviors of apatite, dolomite, calcite and quartz were preliminarily explored through single mineral flotation tests, and the results are shown in Fig. 2 , as shown in Fig. 2 (a), when no depressant is added, under the condition of pH 9, the dosage of N-dodecylaminopropandioate is 6x10 -4When the dosage of the collector N-dodecylaminomalonic acid ester is 6×10-5 mol / L, the recovery rate of the apatite is as high as 80%, the recovery rate of the dolomite is about 40%, and the recovery rates of the quartz and the calcite are both less than 20%, which indicates that the collector N-dodecylaminomalonic acid ester has poor collecting effect on the calcite and the quartz, has the best collecting effect on the apatite, and is expected to be used as a selective collector to realize efficient flotation separation of the apatite from the dolomite, the calcite and the quartz. Fig. 2 (b) shows that, with the addition of the combined depressant, the floatability of the calcite and the dolomite is inhibited, and the recovery rate of the apatite is not affected, and the dosage of the collector N-dodecylaminomalonic acid ester is 6×10-5 mol / L. -4 When the dosage of the collector N-dodecylaminomalonic acid ester is 6×10-5 mol / L, the difference in the floatability of the apatite from the other three gangue minerals is as high as 50%, and the apatite can be effectively enriched.

[0037] The innovative points of the present application are as follows:

[0038] (1) The collector is easily preferentially adsorbed on the surface of the apatite to form a “tridentate coordination”

[0039] The α-carboxylic acid of the collector N-dodecylaminomalonic acid ester is simultaneously ionized to form -COO - in the weak alkaline slurry (pH=8-9). 10 The apatite (Ca + (PO4)6F2) lattice exposes high-density Ca² 2+ sites, and the dolomite (CaMg(CO3)2) and the calcite (CaCO3) surfaces have Mg 2+ or CO3 2- active sites in addition to Ca 2+ . Among them, the Ca-Ca spacing on the surface of the apatite is 3.46 Å; the Ca-Mg spacing on the surface of the dolomite is 3.13 Å, the Mg-Mg spacing is 3.85 Å, and the Ca-Ca spacing is 4.82 Å; and the Ca-Ca spacing on the surface of the calcite is 3.8 Å. The O-O spacing of the carboxylate group in the N-dodecylaminomalonic acid ester is 3.54 Å, which is close to the Ca-Ca atomic spacing on the surface of the apatite, so that the N-dodecylaminomalonic acid ester is easily preferentially matched with the Ca 3- on the surface of the apatite to form a tridentate coordination, and the amino group forms a hydrogen bond with the adjacent PO4 2+ on the surface of the apatite, while the N-dodecylaminomalonic acid ester can only form a bidentate chelation with the Ca 2+ on the surface of the dolomite, and the action with Mg - is weak, and the carbonate lattice spacing is greater than that of the apatite, resulting in low adsorption energy and small coverage. In addition, the combined depressant (sodium hexametaphosphate, sodium lignosulfonate and sodium carboxymethyl starch) is introduced before the collector is added, and when the sodium hexametaphosphate exists, the (PO3) 2+Forming stable five-membered ring, further blocking the adsorption of carboxylate of N-dodecylaminomalonate, making the adsorption density of N-dodecylaminomalonate on apatite surface higher than that on dolomite and calcite, thus providing a selective basis for "positive flotation".

[0040] (2) Quartz surface and collector "electrostatic repulsion-space steric" double shielding

[0041] Under weak alkaline conditions, the collector N-dodecylaminomalonate mainly exists in the form of -COO - and -NH (neutral), which is overall net negative and produces electrostatic repulsion with the same negatively charged quartz surface, and lacks strong enough hydrogen bonding or chemical chelation sites, so it cannot form stable hydrogen bonds or electrostatic adsorption like cationic amines through -NH 3+ , thus resulting in low adsorption density and incomplete hydrophobic layer, which leads to a significant decrease in the collecting ability of quartz. At the same time, the addition of sodium carboxymethyl starch, a combined depressant, forms hydrophilic micelles on the Si-OH layer, and the EO chains of the assistant (sodium dodecylbenzenesulfonate, fatty acid polyoxyethylene ether) extend outward to produce steric hindrance, preventing the alkyl chain of the collector N-dodecylaminomalonate from adsorbing on the quartz surface, making the quartz hydrophilic and remaining in the ore pulp.

[0042] Example 1

[0043] The combined depressant used in this example contains 70%wt of sodium hexametaphosphate, 20%wt of sodium lignosulfonate, and 10%wt of sodium carboxymethyl starch;

[0044] The collector used in this example contains 50%wt of N-dodecylaminomalonate;

[0045] The assistant used in this example contains 60%wt of sodium dodecylbenzenesulfonate and 40%wt of fatty acid polyoxyethylene ether.

[0046] This example uses a certain low-grade collophanite ore sample from Guizhou as the test object, with a raw ore P2O5 grade of 22.15%, SiO2 content of 25.59%, MgO content of 2.46%, and sesquioxide R2O3 content of 4.56% (R represents Fe and Al). The ore is processed according to the following process:

[0047] This example is processed according to the following process:

[0048] S1: Crush and grind the phosphate ore to -0.074mm, with a proportion of 80%, and adjust the water to a pulp concentration of 30%;

[0049] S2: removing gangue minerals by positive flotation: the raw ore is subjected to a roughing, cleaning and scavenging positive flotation process to remove gangue minerals, 800 g / t of sodium carbonate is added to the ore slurry to adjust the pH to 9.0, then 1000 g / t of combined depressant, 600 g / t of collector and 200 g / t of auxiliary agent are added, and after sufficient action, roughing is performed to obtain roughing concentrate and roughing tailings; 500 g / t of combined depressant is added to the roughing concentrate for cleaning to obtain cleaning middlings and phosphorus concentrate, 300 g / t of collector and 50 g / t of auxiliary agent are added to the roughing tailings for scavenging to obtain scavenging middlings and positive flotation tailings, and the cleaning middlings and scavenging middlings are combined and returned to the roughing process of the positive flotation.

[0050] In the above example, a phosphorus concentrate product with a P2O5 grade of 36.45%, a MgO content of 0.89%, a SiO2 content of 6.45%, a R2O3 content of 1.77%, and a P2O5 recovery rate of 84.85% is finally obtained; the product meets the requirements of phosphorus concentrate for the preparation of wet-process phosphoric acid, and can simultaneously remove silicon, magnesium and sesquioxide impurities in medium and low-grade phosphate ores.

[0051] Comparative Example 1

[0052] The other conditions are consistent with those of Example 1, except that no combined depressant is added in the roughing and cleaning of the positive flotation process, and finally a phosphorus concentrate product with a P2O5 grade of 30.66%, a MgO content of 1.25%, a SiO2 content of 6.64%, a R2O3 content of 2.67%, and a P2O5 recovery rate of 82.68% is obtained.

[0053] Comparative Example 2

[0054] The other conditions are consistent with those of Example 1, except that only 70%wt sodium hexametaphosphate and 30%wt sodium lignosulfonate are added in the roughing and cleaning of the positive flotation process, and finally a phosphorus concentrate product with a P2O5 grade of 26.88%, a MgO content of 2.65%, a SiO2 content of 3.86%, a R2O3 content of 3.12%, and a P2O5 recovery rate of 78.72% is obtained.

[0055] Comparative Example 3

[0056] The other conditions are consistent with those of Example 1, except that only 70%wt sodium hexametaphosphate and 30%wt sodium carboxymethyl starch are added in the roughing and cleaning of the positive flotation process, and finally a phosphorus concentrate product with a P2O5 grade of 27.65%, a MgO content of 2.36%, a SiO2 content of 3.24%, a R2O3 content of 3.65%, and a P2O5 recovery rate of 77.43% is obtained.

[0057] Comparative Example 4

[0058] The other conditions are consistent with example 1, the difference is that no additives are added in the roughing and scavenging of the positive flotation process section, finally the P2O5 grade is 27.12%, the MgO content is 3.65%, the SiO2 content is 7.04%, the R2O3 content is 3.54%, and the P2O5 recovery rate is 77.24% of the phosphate concentrate product.

[0059] Comparative example 5

[0060] The other conditions are consistent with example 1, the difference is that only sodium dodecyl sulfonate is added as an additive in the roughing and scavenging of the positive flotation process section, finally the P2O5 grade is 25.46%, the MgO content is 3.98%, the SiO2 content is 7.25%, the R2O3 content is 3.94%, and the P2O5 recovery rate is 76.15% of the phosphate concentrate product.

[0061] Comparative example 6

[0062] The other conditions are consistent with example 1, the difference is that only fatty acid polyoxyethylene ether is added as an additive in the roughing and scavenging of the positive flotation process section, finally the P2O5 grade is 26.32%, the MgO content is 4.12%, the SiO2 content is 6.89%, the R2O3 content is 4.13%, and the P2O5 recovery rate is 76.43% of the phosphate concentrate product.

[0063] The above only describes the preferred embodiments of the present application and does not limit the present application in any form. Although the present application has been disclosed as above, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above-mentioned technical content without departing from the scope of the present application, and any simple modification, equivalent change and modification of the above-mentioned embodiments based on the technical essence of the present application are still within the scope of the present application.

Claims

1. A beneficiation process for simultaneous removal of siliceous and magnesian and sesquioxide impurities from phosphate ores, characterized in that, The method comprises the following steps: S1, crushing and grinding the phosphate ore to -0.074 mm, and preparing a slurry; S2, performing positive flotation under weak alkaline conditions, adding sodium carbonate as a pH regulator to adjust the pH of the slurry to 8-9, then adding a combined depressant, a collector and an additive, and then performing one roughing, one cleaning and one scavenging to simultaneously remove dolomite, calcite, quartz and sesquioxide impurities, to obtain cleaned concentrate, scavenged tailings, middlings from the cleaning operation and middlings from the scavenging operation, which are returned to the roughing operation, and the cleaned concentrate is the phosphate concentrate.

2. The process according to claim 1, characterized in that: In S1, the P2O5 grade of the phosphate ore is 20%-30%, the SiO2 content is 12-25%, the MgO content is 3-5%, and the sesquioxide R2O3 content is 3.5-6%, where R represents Fe and Al.

3. The process as claimed in claim 1, wherein the process for simultaneous removal of silica, magnesium and sesquioxide impurities from phosphate rock is characterized by: In S1, the -0.074 mm particle size fraction accounts for more than 75%, and the slurry concentration is 25%-35%.

4. The process as claimed in claim 1, wherein the process for simultaneous removal of silica and magnesium and sesquioxide impurities from phosphate rock is characterized by: In S2, the depressant is one or any combination of sodium hexametaphosphate, sodium lignosulfonate and sodium carboxymethyl starch; the collector is N-dodecylaminopropandioate; and the additive is sodium dodecylbenzenesulfonate and / or fatty acid polyoxyethylene ether.

5. The process as claimed in claim 1, wherein the process for simultaneous removal of silica, magnesium and sesquioxide impurities from phosphate rock comprises the steps of: In S2, the one roughing, one cleaning and one scavenging are specifically as follows: In the roughing operation, a pH regulator is added to the slurry to adjust the pH, and then a combined depressant, a collector and an additive are added; In the cleaning operation, a combined depressant is added to the rough concentrate obtained in the roughing operation for cleaning; In the scavenging operation, a collector and an additive are added to the roughing tailings obtained in the roughing operation for scavenging.

6. The process as claimed in claim 1, wherein the process for simultaneous removal of silica, magnesium and sesquioxide impurities from phosphate rock comprises the steps of: In S2, in the roughing operation, the sodium carbonate is used in an amount of 600-1200 g / t, the combined depressant is used in an amount of 800-1200 g / t, the collector is used in an amount of 400-800 g / t, and the additive is used in an amount of 100-400 g / t; In the cleaning operation, the combined depressant is added in an amount of 200-600 g / t; In the scavenging operation, the collector is added in an amount of 200-500 g / t, and the additive is added in an amount of 20-70 g / t.

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