A process for synchronous flotation and impurity removal of phosphogypsum

Abstract

The present invention belongs to the field of purification of phosphogypsum, and particularly relates to a synchronous flotation process for removing impurities from phosphogypsum. The synchronous flotation process for removing impurities provided by the present invention comprises: after re-slurrying the phosphogypsum, sequentially adding a modified regulator, a foaming agent, and a collector, and then performing a first-stage reverse flotation operation to obtain a rough concentrate and foam product I; mixing the obtained rough concentrate with the foaming agent and the collector again, and entering a second-stage reverse flotation operation to obtain a final concentrate and foam product II; performing a blank scavenging operation I on foam product II to obtain foam product III and middling I, and returning middling I to the first-stage reverse flotation operation; mixing foam product I and foam product III, adding a collector, and performing a scavenging operation II to obtain tailings and middling II, and returning middling II to scavenging operation I. The present invention is simple and efficient, and can synchronously remove various impurities such as phosphorus, fluorine, silicon, and organic matter in phosphogypsum.

Description

Technical Field

[0001] The present invention relates to the field of purification of phosphogypsum, and particularly to a process for synchronous flotation and impurity removal of phosphogypsum. Background Art

[0002] The production of gypsum building materials is one of the important ways to consume phosphogypsum. However, due to the strong acidity of phosphogypsum, unstable quality, and the presence of harmful impurities such as soluble and insoluble phosphorus, fluorine, and silicon, the product quality is poor, which in turn affects the consumption of phosphogypsum.

[0003] Application No. CN 112871457A discloses a method for purifying and removing impurities from phosphogypsum. This method effectively removes organic matter in the phosphogypsum concentrate through reverse flotation decolorization and forward flotation impurity removal of phosphogypsum, greatly improves the whiteness of gypsum, and the contents of soluble phosphorus and fluorine meet the requirements of first-class products for phosphogypsum building materials.

[0004] Publication No. CN105537004A discloses a method for preparing a flotation collector for phosphogypsum. By using this reagent for forward flotation of phosphogypsum, the silicon content in phosphogypsum can be effectively reduced and the grade can be improved.

[0005] Publication No. CN114308398A discloses a method for flotation washing, decolorization, purification of phosphogypsum. After three times of reverse flotation and water washing of phosphogypsum, the silicon and organic matter contents in phosphogypsum can be effectively reduced, and the whiteness and grade can be improved.

[0006] For the purification pretreatment of phosphogypsum, a variety of patented technologies have been published. However, these methods still have the following problems: the process is complex and there are many process steps. Moreover, water-soluble and insoluble impurities cannot be effectively removed to achieve the purpose of improving the whiteness, purity, and pH value of purified phosphogypsum. These problems seriously affect the purification treatment of phosphogypsum.

[0007] Therefore, finding a new method for purifying and removing impurities from phosphogypsum has become an urgent problem in this field. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for purifying phosphogypsum. The method of the present invention is simple, efficient, and the obtained purified phosphogypsum can provide high-quality raw materials for building materials production.

[0009] A process for synchronous flotation and impurity removal of phosphogypsum includes the following steps:

[0010] (1) After re-slurrying the phosphogypsum, a modified regulator, a foaming agent, and a collector are sequentially added for pulp conditioning to obtain a feed pulp for flotation.

[0011] (2) The feed pulp obtained in step (1) is introduced into the reverse flotation operation I to obtain a rough concentrate and a foam product I.

[0012] (3) After remixing the rough concentrate obtained in step (2) with a frother and a collector, carry out reverse flotation operation II to obtain a final concentrate and foam product II;

[0013] (4) Carry out blank scavenging operation I on the foam product II obtained in step (3) to obtain middling I and foam product III, and return middling I to reverse flotation operation I.

[0014] (5) After mixing foam product I and foam product III obtained in step (1) and adding a collector, carry out scavenging operation II to obtain a final tailing and middling II, and return middling II to scavenging operation I.

[0015] In the said step (1), the grade of phosphogypsum is 80 - 90%, the whiteness is 15 - 25%, and the slurry concentration after re-slurrying is controlled at 35 - 40%.

[0016] In the said step (1), the modification regulator is calcium hydroxide or calcium oxide; the dosage of the modification regulator is 3 - 5 kg / t.

[0017] In the said modification regulator, a mixture of water glass, coconut oil fatty acid diethanolamide, chitosan, and sorbitan oleate is further added, and the addition amount is 5 - 50% of the total amount of the modification regulator.

[0018] In the preferred scheme, the mass ratio of calcium oxide, water glass, coconut oil fatty acid diethanolamide, chitosan, and sorbitan oleate in the said modification regulator is 6:1 - 2:1 - 2:0.3 - 0.8:0.3 - 0.8.

[0019] In the said steps (1) and (3), the frother is a mixture of diesel oil and No. 2 oil with a mass ratio of 3 - 5:5 - 7. The dosage of the frother is 0.1 - 0.4 kg / t.

[0020] In the preferred scheme, the dosage of the frother in step (1) is 0.1 - 0.3 kg / t. The dosage of the frother in step (3) is 0.2 - 0.4 kg / t.

[0021] In the said steps (1), (3), and (5), the collector is a compound fatty acid collector XF - 02, specifically obtained by mixing palmitic acid, stearic acid, oleic acid, and linoleic acid in a mass ratio of 20 - 25:5 - 10:12 - 25:40 - 55, saponifying to obtain mixed fatty acid sodium salts, and using the obtained mixed fatty acid sodium salts to mix with methyl isopropyl methanol in a mass ratio of 8 - 9:1 - 2, with a dosage of 0.1 - 0.6 kg / t.

[0022] The dosages of the collector in the said steps (1), (3), and (5) are 0.4 - 0.6 kg / t, 0.4 - 0.6 kg / t, or 0.1 - 0.3 kg / t respectively.

[0023] Compared with the prior art, the provided phosphogypsum synchronous flotation process of the present invention: (1) circumvents the dilemma that different impurities such as water-soluble impurities, organic matter, solid-phase phosphorus, and silicon in the conventional phosphogypsum purification and impurity removal process need to be treated separately, and can achieve obtaining high-quality gypsum building material production raw materials with qualified whiteness, purity, pH value, water-soluble phosphorus, fluorine, etc. in one step; (2) through the synergistic effect of reagents such as regulators and foaming agents, improves the separation effect of each reagent in the flotation process, and at the same time, with the two-rougher and two-scavenger separation process, while ensuring the foam effect, further reduces the tailing production and reduces the generation of secondary solid waste; (3) thanks to the use of regulators, the flotation is carried out in a slightly alkaline environment, and the flotation recycled water can be fully recycled, alleviating the wastewater treatment problem caused by the water washing of traditional flotation refined gypsum. Specific implementation examples

[0024] Example 1

[0025] In this example, the modified regulator is a mixture of calcium oxide: sodium silicate: coconut oil fatty acid diethanolamide: chitosan: sorbitan oleate with a mass ratio of 6:1.5:1.5:0.5:0.5.

[0026] The foaming agent is a mixture of diesel oil: No. 2 oil with a mass ratio of 4:6.

[0027] The collector is a compound fatty acid collector XF-02, specifically obtained by mixing palmitic acid, stearic acid, oleic acid, and linoleic acid in a mass ratio of 20:5:25:40, and then saponifying to obtain mixed fatty acid sodium salts. The obtained mixed fatty acid sodium salts are mixed with methyl isopropyl carbinol in a mass ratio of 9:1.

[0028] Processing phosphogypsum from a certain phosphorus chemical enterprise (purity of dihydrate calcium sulfate is 85%, whiteness is 24%, water-soluble phosphorus is 0.91%, water-soluble fluorine is 0.75%, pH value is 2.2)

[0029] (1) After re-slurrying the phosphogypsum, successively add 5 kg / t of the modified regulator, 0.25 kg / t of the foaming agent, and 0.5 kg / t of the collector for pulp conditioning to obtain the feed pulp for flotation;

[0030] (2) Introduce the feed pulp obtained in step (1) into the reverse flotation operation I to obtain rough concentrate and foam product I;

[0031] (3) Successively add 0.35 kg / t of the foaming agent and 0.6 kg / t of the collector to the rough concentrate obtained in step (2), mix again, and then carry out the reverse flotation operation II to obtain the final concentrate and foam product II;

[0032] (4) Conduct a blank scavenging operation I on the foam product II obtained in step (3) to obtain middling I and foam product III, and return middling I to the reverse flotation operation I.

[0033] (5) Mix the foam product I and the foam product III obtained in step (1), add 0.1 kg / t of collector, and perform the scavenging operation II to obtain the final tailings and the middlings II. The middlings II are returned to the scavenging operation I.

[0034] The purified phosphogypsum obtained in this example has a grade of 92.17%, a yield of 86.28%, water-soluble phosphorus of 0.16%, and water-soluble fluorine of 0.11%. The purified phosphogypsum meets the requirements of first-class products in GB / T23456-2018, with a whiteness of 56% and a pH value of 4.8, and is a high-quality raw material for building materials production.

[0035] Example 2

[0036] The method and steps are the same as those in Example 1, except that the modified modifier is not added in step (1). The purity of the purified phosphogypsum obtained is 90.89%, the yield is 84.31%, the water-soluble phosphorus is 0.35%, the water-soluble fluorine is 0.26%, which does not meet the requirements of first-class products in GB / T23456-2018, with a whiteness of 59% and a pH value of 3.2.

[0037] The method and steps are the same as those in Example 1, except that the proportion of lime in the modified modifier in step (1) is reduced to 4 (a mixture of calcium oxide: sodium silicate: coconut oil fatty acid diethanolamide: chitosan: sorbitan oleate with a mass ratio of 4:2:2:1:1). The purity of the purified phosphogypsum obtained is 91.77%, the yield is 85.98%, the water-soluble phosphorus is 0.27%, the water-soluble fluorine is 0.19%, which does not meet the requirements of first-class products in GB / T23456-2018, with a whiteness of 57% and a pH value of 3.8.

[0038] The method and steps are the same as those in Example 1, except that the proportion of lime in the modified modifier in step (1) is reduced to 7 (a mixture of calcium oxide: sodium silicate: coconut oil fatty acid diethanolamide: chitosan: sorbitan oleate with a mass ratio of 7:1:1:0.5:0.5). The purity of the purified phosphogypsum obtained is 91.53%, the yield is 86.84%, the water-soluble phosphorus is 0.14%, the water-soluble fluorine is 0.09%, which meets the requirements of first-class products in GB / T23456-2018, with a whiteness of 50% and a pH value of 5.5. The whiteness of the product is too low, which is not conducive to downstream utilization.

[0039] In the analysis of the influence of the modified regulator in this example, it was found that after adding the modified regulator, the sorting performance of the reagent can be effectively improved. This is because the modified regulator has a good dispersion effect and can optimize the slurry environment. Although the whiteness of the obtained purified phosphogypsum decreases, the yield and purity are higher. At the same time, under the action of calcium oxide, the pH of the slurry increases, and the water-soluble phosphorus and fluorine contents decrease, realizing the removal of water-soluble impurities in the gypsum. However, if the dosage of calcium oxide is too large, the fine-grained precipitates in the slurry increase, resulting in the deterioration of the flotation decolorization effect and a sharp decrease in whiteness. If the dosage of calcium oxide is reduced, the water-soluble impurities cannot be effectively removed, and the water-soluble phosphorus and fluorine contents of the product cannot meet the standards, failing to meet the requirements of Grade 1 products in GB / T 23456-2018.

[0040] Example 3

[0041] The method and steps are the same as those in Example 1, except that in step (1), the modified regulator is changed to (a mixture of calcium oxide: sodium silicate: sodium hexametaphosphate: chitosan: polyethylene glycol (PEG-800) with a mass ratio of 6:1.5:1.5:0.5:0.5). The obtained purified phosphogypsum has a purity of 91.16%, a yield of 81.33%, a water-soluble phosphorus content of 0.15%, and a water-soluble fluorine content of 0.13%, meeting the requirements of Grade 1 products in GB / T 23456-2018, with a whiteness of 51%, a pH value of 4.7, a relatively low yield, and poor concentrate indexes.

[0042] The method and steps are the same as those in Example 1, except that in step (1), coconut oil fatty acid diethanolamide is not added to the modified regulator (a mixture of calcium oxide: sodium silicate: chitosan: sorbitan oleate with a mass ratio of 6: 1.5:0.5:0.5). The obtained purified phosphogypsum has a purity of 90.97%, a yield of 83.34%, a water-soluble phosphorus content of 0.15%, and a water-soluble fluorine content of 0.13%, meeting the requirements of Grade 1 products in GB / T 23456-2018, with a whiteness of 49%, a pH value of 4.7, a relatively low whiteness, and in the flotation process, the foam is too rich and the process stability is poor.

[0043] The method and steps are the same as those in Example 1, except that in step (1), sorbitan oleate is not added to the modified regulator (a mixture of calcium oxide: sodium silicate: coconut oil fatty acid diethanolamide: chitosan with a mass ratio of 6:1.5:1.5:0.5). The obtained purified phosphogypsum has a purity of 90.05%, a yield of 82.27%, a water-soluble phosphorus content of 0.14%, and a water-soluble fluorine content of 0.11%, meeting the requirements of Grade 1 products in GB / T 23456-2018, with a whiteness of 47%, a pH value of 4.6, too rich foam, poor process stability, and a relatively low whiteness.

[0044] In the analysis of the influence of the modification regulator in this example, it is found that organic matter is one of the main factors affecting the whiteness of phosphogypsum. When the water glass dispersant is lacking, the organic matter and impurities such as silicon in the fine particle size in the material cannot be dispersed, the performance of the reagent deteriorates, the separability decreases, and the whiteness, purity and yield all decrease to varying degrees; when sorbitan oleate is lacking, the foam viscosity increases and it is not easy to break, the separability of the reagent decreases, and the fine particle size phosphogypsum is discharged with the tailings, increasing the amount of tailings; coconut oil fatty acid diethanolamide has a synergistic effect with the foaming agent and the collector, which can improve the reagent performance of the foaming agent and the collector, and the whiteness and purity of the concentrate will both increase. The conventional regulators used in flotation do not promote the flotation of phosphogypsum, and both the separability and the concentrate indexes are poor.

[0045] Example 4

[0046] The method and steps are the same as those in Example 1, only in step (1), step (3) and step (5), the collector used is replaced with a cationic collector mainly composed of dodecylamine acetate, the flotation becomes positive flotation, and the foam viscosity is large, the decolorization effect deteriorates, and the foam is difficult to control.

[0047] Example 5

[0048] The same modification regulator, foaming agent and collector as in Example 1 are used to enter the following implementation plan:

[0049] (1) After the phosphogypsum is repulped, 5 kg / t of the modification regulator, 0.7 kg / t of the foaming agent and 1.1 kg / t of the collector are added in sequence for pulp conditioning to obtain the feed pulp.

[0050] (2) The feed pulp obtained in step (1) is introduced into the reverse flotation operation to obtain the concentrate and foam product I.

[0051] (3) A blank scavenging operation I is carried out on the foam product I obtained in step (2) to obtain the middling I and foam product II, and the middling I is returned to the reverse flotation operation.

[0052] (4) 0.1 kg / t of the collector is added to the foam product I obtained in step (3) for scavenging operation II to obtain the final tailings and middling II, and the middling II is returned to the scavenging operation I.

[0053] The purified phosphogypsum obtained in this example has a grade of 90.14%, a yield of 87.13%, a water-soluble phosphorus of 0.17%, and a water-soluble fluorine of 0.12%. The purified phosphogypsum meets the requirements of first-class products in GB / T23456-2018, with a whiteness of 49% and a pH value of 4.8, and the whiteness is on the low side.

[0054] In the analysis of the influence of the roughing operation in this example, it is found that the operation of adopting a segmented roughing operation can extend the action time of the reagent, improve the separability performance of the reagent, and the purity and whiteness of the concentrate will both be greatly improved.

[0055] Example 6

[0056] Using the same modifying regulator, foaming agent, and collector as in Example 1, the following implementation plan is carried out:

[0057] (1) After re-slurrying the phosphogypsum, 5 kg / t of modifying regulator, 0.25 kg / t of foaming agent, and 0.5 kg / t of collector are added in sequence for pulp conditioning to obtain the feed pulp for separation;

[0058] (2) The feed pulp for separation obtained in step (1) is introduced into the reverse flotation operation I to obtain rough concentrate and foam product I;

[0059] (3) 0.35 kg / t of foaming agent and 0.6 kg / t of collector are added to the rough concentrate obtained in step (2) in sequence. After remixing, reverse flotation operation II is carried out to obtain the final concentrate and foam product II;

[0060] (4) After mixing the foam product I and foam product II obtained in step (2), 0.1 kg / t of collector is added for scavenging operation to obtain the final tailings and middlings. The middlings are returned to the reverse flotation operation I.

[0061] The purified phosphogypsum obtained in this example has a grade of 90.91%, a yield of 84.92%, water-soluble phosphorus of 0.17%, and water-soluble fluorine of 0.15%. The purified phosphogypsum meets the requirements of first-grade products in GB / T23456-2018, with a whiteness of 50% and a pH value of 4.8. The whiteness of the product is relatively low.

[0062] In analyzing the influence of the scavenging operation in this example, it was found that when directly scavenging the tailings obtained from the first and second stages of rough selection after mixing, the concentrate yield, grade, and whiteness all decreased to varying degrees. The main reason for the analysis is that the quality of the tailings obtained in the first stage is poor. When directly combined with the tailings of the second stage of rough selection for scavenging, the quality of the obtained middlings is poor. Returning to the first stage of rough selection will lead to a decrease in the whiteness and purity of the raw materials for rough selection, ultimately resulting in the deterioration of the concentrate index; at the same time, the quality of the second-stage tailings is relatively good, and the scavenging operation causes a large loss of products, resulting in a decrease in the concentrate yield.

[0063] Example 7

[0064] The method steps are the same as in Example 1, except that the middlings I obtained in step (4) are returned to the reverse flotation operation II in step (3). The purified phosphogypsum obtained in this example has a grade of 91.14%, a yield of 87.01%, water-soluble phosphorus of 0.19%, and water-soluble fluorine of 0.16%. The purified phosphogypsum meets the requirements of first-grade products in GB / T23456-2018, with a whiteness of 52% and a pH value of 4.8. The whiteness of the product is relatively low.

[0065] In the analysis of the influence of the intermediate ore return point in this embodiment, it is found that when the intermediate ore I is returned to the second stage of rough flotation, the concentrate yield increases slightly, but the grade and whiteness decrease significantly. The main reason for the analysis is that the quality of the intermediate ore I is poorer than that of the concentrate in the first stage of rough flotation. After mixing, the purity and whiteness of the slurry fed into the second stage of rough flotation are reduced, resulting in a decline in indicators.

[0066] Example 8

[0067] (1)After re-slurrying the phosphogypsum, 5 kg / t of a modified regulator, 0.25 kg / t of a foaming agent, and 0.5 kg / t of a collector are added in sequence for pulp conditioning to obtain the feed slurry for flotation.

[0068] (2)The feed slurry obtained in step (1) is introduced into the first stage of reverse flotation operation to obtain rough concentrate and foam product I.

[0069] (3)0.35 kg / t of a foaming agent and 0.6 kg / t of a collector are added to the rough concentrate obtained in step (2) in sequence. After remixing, the second stage of reverse flotation operation is carried out to obtain the final concentrate and foam product II.

[0070] (4)The foam product I and foam product II obtained in step (2) are mixed and then subjected to the first stage of scavenging operation to obtain foam product III and intermediate ore I. Intermediate ore I is returned to the first stage of reverse flotation operation.

[0071] (5)The foam product III obtained in step (4) is subjected to the second stage of scavenging operation to obtain the final tailings and intermediate ore II. Intermediate ore II is returned to the first stage of scavenging operation.

[0072] The grade of the purified phosphogypsum obtained in this embodiment is 90.09%, the yield is 86.34%, the water-soluble phosphorus is 0.17%, and the water-soluble fluorine is 0.17%. The purified phosphogypsum meets the requirements of Grade I in GB / T23456-2018, with a whiteness of 49% and a pH value of 4.8.

[0073] In the analysis of the sequential scavenging operation in this embodiment, it is found that two-stage scavenging can increase the concentrate yield, but not only fails to solve the problem of the decline in concentrate indicators, but also further deteriorates the indicators.

[0074] Example 9

[0075] The method steps are the same as those in Example 8, except that 0.2 kg / t of a collector is added to the concentrate obtained in step (3) for a cleaning operation to obtain the final concentrate and foam product III. Foam product III is returned to the first stage of reverse flotation operation in step (1).

[0076] (4)The foam product I and foam product II obtained in step (2) are mixed and then subjected to the first stage of scavenging operation to obtain foam product III and intermediate ore I. Intermediate ore I is returned to the first stage of reverse flotation operation.

[0077] (5) Conduct the second scavenging operation on the foam product III obtained in step (4) to obtain the final tailings and the second middlings, and return the second middlings to the first scavenging operation.

[0078] The purified phosphogypsum obtained in this example has a grade of 92.04%, a yield of 85.57%, a water-soluble phosphorus content of 0.16%, and a water-soluble fluorine content of 0.14%. The purified phosphogypsum meets the requirements of the first-grade product in GB / T23456-2018, with a whiteness of 55% and a pH value of 4.8.

[0079] In analyzing the influence of the two roughing, one cleaning, and two scavenging processes in this example, it was found that adding one more cleaning operation on the basis of Example 8 can effectively improve the concentrate index. However, adding one more cleaning operation increases the flotation process and the cost.

[0080] The above is only the preferred implementation mode of the present invention, rather than a limitation on the implementation plan. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several improvements and changes are made, and these all belong to the protection scope of the present invention.

Claims

1. A process for synchronous flotation and impurity removal of phosphogypsum, characterized in that, It includes the following steps: (1) After re-slurrying phosphogypsum, successively add a modification regulator, a foaming agent, and a collector for pulp conditioning to obtain a feed pulp for separation; (2) Introduce the feed pulp for separation obtained in step (1) into reverse flotation operation I to obtain a rough concentrate and foam product I; (3) After remixing the rough concentrate obtained in step (2) with a foaming agent and a collector, conduct reverse flotation operation II to obtain a final concentrate and foam product II; (4) Conduct blank scavenging operation I on the foam product II obtained in step (3) to obtain middling I and foam product III, and return middling I to reverse flotation operation I; (5) Mix foam product I and foam product III obtained in step (1), add a collector, and conduct scavenging operation II to obtain a final tailing and middling II, and return middling II to scavenging operation I.

2. The phosphorus gypsum synchronous flotation impurity removal process according to claim 1, characterized in that, In step (1), the phosphogypsum has a grade of 80 - 90% and a whiteness of 15 - 25%. After re-slurrying, the pulp concentration is controlled at 35 - 40%.

3. The phosphorus gypsum synchronous flotation impurity removal process according to claim 1, characterized in that, In step (1), the modification regulator is calcium hydroxide or calcium oxide; the dosage of the modification regulator is 3 - 5 kg / t.

4. A process for synchronous flotation and impurity removal of phosphogypsum according to claim 3, characterized in that, The modification regulator also contains a mixture of water glass, coconut oil fatty acid diethanolamide, chitosan, and sorbitan oleate, and the addition amount is 5 - 50% of the total amount of the modification regulator.

5. A process for synchronous flotation and impurity removal of phosphogypsum according to claim 4, characterized in that, In the modification regulator, the mass ratio of calcium oxide, water glass, coconut oil fatty acid diethanolamide, chitosan, and sorbitan oleate is 6:1 - 2:1 - 2:0.3 - 0.8:0.3 - 0.

8.

6. A process for synchronous flotation and impurity removal of phosphogypsum according to claim 1, characterized in that, In steps (1) and (3), the foaming agent is a mixture of diesel oil and No. 2 oil with a mass ratio of 3 - 5:5 - 7, and the dosage of the foaming agent is 0.1 - 0.4 kg / t.

7. A process for synchronous flotation and impurity removal of phosphogypsum according to claim 1, characterized in that, In steps (1), (3), and (5), the collector is a compound fatty acid collector XF - 02, specifically prepared by mixing palmitic acid, stearic acid, oleic acid, and linoleic acid in a mass ratio of 20 - 25:5 - 10:12 - 25:40 - 55, saponifying to obtain a mixed fatty acid sodium salt, and mixing the obtained mixed fatty acid sodium salt with methyl isopropyl carbinol in a mass ratio of 8 - 9:1 - 2, with a dosage of 0.1 - 0.6 kg / t.