A kind of phosphogypsum reverse flotation whitening and impurity removal agent and its preparation method and process

Abstract

The present invention relates to a phosphogypsum reverse flotation whitening and impurity removal agent and a preparation method and a process method thereof, belonging to the technical field of phosphorus chemical solid waste treatment, and solving the problems of low organic carbon selectivity, poor whitening effect, poor acid resistance, and weak ability to remove iron impurities in phosphogypsum in the prior art. A phosphogypsum reverse flotation whitening and impurity removal agent, the agent is tributyl phosphate, pineneol, a fatty alkyl (R) carbon chain length C 12 ~C 20 The carbon chain length of the fatty primary amine (R-NH2) and fatty alkyl (R) is C 12 ~C 20 The reverse flotation whitening and impurity removal agent for phosphogypsum provided by the present invention is adaptable to strong acid environments, has high selectivity for organic carbon in acidic environments, can capture black organic carbon, iron impurities and silicon dioxide at the same time, and has the performance of a frother. After "two reverse and two positive" flotation, the whiteness of phosphogypsum is increased from 35% to 74.5%, and the grade (calculated as CaSO4.2H2O) is increased from 90% to 98.2%.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphorus chemical solid waste treatment, and specifically relates to a phosphogypsum reverse flotation whitening and impurity removal agent and a preparation method and a process method thereof. Background Art

[0002] Phosphogypsum is a by-product in the production of wet-process phosphoric acid. More than 90% of my country's wet-process phosphoric acid adopts the dihydrate process, and 4.5 to 5 tons of phosphogypsum are produced for every ton of phosphoric acid produced. As the main by-product in my country's phosphate fertilizer and phosphorus chemical industry, phosphogypsum is discharged nearly 75 million tons per year. In China, the utilization rate of phosphogypsum is only about 40% at this stage, resulting in large-scale stockpiling. It not only occupies a large amount of land resources and causes environmental pollution, but also has high investment and operation costs for slag yards, which imposes a great burden on phosphate fertilizer and phosphorus chemical companies. The purification and resource utilization of phosphogypsum have become the key to the healthy and sustainable development of the phosphate fertilizer and phosphorus chemical industry. The production of phosphogypsum is shown in the following formula:

[0003] Ca 10 (PO4)6F2+10H2SO4+20H2O→6H3PO4+10CaSO4·2H2O+2HF

[0004] The premise of utilizing phosphogypsum is the quality improvement and purification of phosphogypsum. Phosphogypsum contains many harmful impurities such as phosphorus, fluorine, and organic matter. These harmful impurities have a great impact on the performance of phosphogypsum products. Taking the whiteness of phosphogypsum as an example, phosphogypsum is mostly gray or gray-black, which seriously limits the back-end application scope of phosphogypsum. Organic carbon and metal impurities in phosphogypsum are the main reasons for the gray or gray-black color of phosphogypsum. Metal impurities, especially iron impurities, have a great impact on the whiteness of phosphogypsum. Low whiteness not only affects the value-added utilization of phosphogypsum in building materials, but also iron impurities produce redness when phosphogypsum is prepared into anhydrous gypsum at high temperature (caused by the conversion of divalent iron impurities into red iron oxide). Whitening and removing impurities from phosphogypsum can greatly improve its utilization value, and can also replace natural gypsum with limited reserves, reduce the damage to the ecological environment caused by solid waste storage, and improve resource utilization.

[0005] Flotation can effectively remove organic carbon, iron impurities and impurities such as silicon dioxide in phosphogypsum, greatly improve its whiteness, expand its application in lightweight thermal insulation gypsum boards, phase change energy storage materials and architectural decorations, and improve the application value of phosphogypsum. Patent CN109734341A discloses a method for improving the whiteness of phosphogypsum by physical and chemical means, but this method adds a large amount of pH adjuster and surfactant, and adopts gravity separation (with flotation function) and magnetic separation equipment, and the process route is relatively complicated. In addition, this method cannot effectively remove non-magnetic impurities such as silicon dioxide and pyrite in phosphogypsum. Patent CN111302377A discloses a method for removing impurities and whitening phosphogypsum, but this method requires processes such as acid leaching, flotation, gravity separation, and requires a large amount of sulfuric acid and pH adjuster, and the process route is relatively complicated and economical.

[0006] Flotation collector is the key to determine the flotation effect. Existing flotation agents have poor selectivity under acidic conditions, low selectivity for organic carbon, poor whitening effect, and weak ability to remove iron impurities in phosphogypsum. Therefore, there is an urgent need for a new, efficient, acid-resistant, phosphogypsum flotation whitening and quality-improving collector that can simultaneously remove organic carbon, iron impurities and silica in phosphogypsum.

[0007] In summary, in view of the current problems of poor whitening effect and weak collecting capacity of flotation collectors for whitening and removing impurities from phosphogypsum, it is of great significance to develop a reverse flotation whitening and impurity removal agent for phosphogypsum. Summary of the invention

[0008] In view of the above analysis, the embodiments of the present invention aim to provide a phosphogypsum reverse flotation whitening and impurity removal agent and a preparation method and process method thereof, so as to solve the problems in the prior art that the phosphogypsum whitening and impurity removal flotation agent has low organic carbon selectivity, poor whitening effect, poor acid resistance, and weak ability to remove iron impurities in phosphogypsum.

[0009] The main purpose of the present invention is achieved through the following technical solutions:

[0010] The invention provides a phosphogypsum reverse flotation whitening and impurity removal agent, wherein the agent comprises tributyl phosphate, terpineol, a fatty alkyl (R) carbon chain length of C 12 ~C 20 The carbon chain length of the fatty primary amine (R-NH2) and fatty alkyl (R) is C 12 ~C 20 A compound agent of dimethyl tertiary amine (RN(CH3)2).

[0011] Furthermore, the fatty primary amine (R-NH2) is one or more of dodecylamine, tetradecylamine, hexadecylamine and octadecylamine.

[0012] Furthermore, the dimethyl tertiary amine (RN(CH3)2) is one or more of dodecyl dimethyl tertiary amine, tetradecyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, and octadecyl dimethyl tertiary amine.

[0013] Furthermore, the raw material composition of the agent is calculated by mass percentage as follows: tributyl phosphate: 5% to 15%; terpineol: 5% to 15%; the carbon chain length of the fatty alkyl (R) is C 12 ~C 20 Fatty primary amine (R-NH2) in the range of 30% to 60%; fatty alkyl (R) carbon chain length is C 12 ~C 20 Range of dimethyl tertiary amine (RN(CH3)2): 20% to 40%.

[0014] The present invention also provides a method for preparing a phosphogypsum reverse flotation whitening and impurity removal agent, which is used to prepare the phosphogypsum reverse flotation whitening and impurity removal agent, comprising:

[0015] Tributyl phosphate, pineneol and fatty primary amine are added to dimethyl tertiary amine solution, and mechanically stirred to obtain a reverse flotation agent solution system; during the stirring and homogenization of the reverse flotation agent solution system, a certain amount of water is added to adjust the mass fraction of the reverse flotation agent solution.

[0016] Furthermore, the mass fraction of the dimethyl tertiary amine solution is 30-40%, and the dimethyl tertiary amine solution is activated before use.

[0017] Furthermore, the mechanical stirring time is 1-2 hours, and in the reverse flotation agent solution system, the mass fraction of the reverse flotation agent is 5-7%.

[0018] The present invention also provides a phosphogypsum reverse flotation whitening and impurity removal process, which uses the phosphogypsum reverse flotation whitening and impurity removal agent or the phosphogypsum reverse flotation whitening and impurity removal agent prepared by the preparation method of the present invention, comprising the following steps:

[0019] Step 1: connect two cyclone-static microbubble flotation columns in series;

[0020] Step 2: transporting the phosphogypsum to be treated to a slurry mixing tank for slurry mixing to obtain phosphogypsum slurry;

[0021] Step 3: The phosphogypsum slurry in the slurry mixing tank is pumped into the first cyclone-static microbubble flotation column, and a reverse flotation agent is added to perform the first reverse flotation to obtain the first slurry; the first slurry is pumped into the second cyclone-static microbubble flotation column, and the reverse flotation agent same as the first reverse flotation is added to perform the second reverse flotation to obtain the phosphogypsum concentrate;

[0022] Step 4: The phosphogypsum concentrate obtained after two reverse flotation treatments is pumped into a plate and frame filter press for dehydration. After dehydration, the concentrate is dried to obtain whitened and impurity-free phosphogypsum.

[0023] Furthermore, in step 2, the pH of the phosphogypsum slurry is 1 to 3, and the mass concentration of the slurry is 30% to 40%.

[0024] The present invention also provides a phosphogypsum whitening and impurity removal process, which uses the phosphogypsum reverse flotation whitening and impurity removal agent or the phosphogypsum reverse flotation whitening and impurity removal agent prepared by the preparation method of the present invention, comprising the following steps:

[0025] Step 1: connect four cyclone-static microbubble flotation columns in series;

[0026] Step 2: transporting the phosphogypsum to be treated to a slurry mixing tank for slurry mixing to obtain phosphogypsum slurry;

[0027] Step 3: The phosphogypsum slurry in the slurry mixing tank is pumped into the first cyclone-static microbubble flotation column, and a reverse flotation agent is added to perform the first reverse flotation to obtain the first slurry; the first slurry is pumped into the second cyclone-static microbubble flotation column, and the reverse flotation agent same as that of the first reverse flotation is added to perform the second reverse flotation to obtain the second slurry;

[0028] Step 4: The second slurry is pumped into the third cyclone-static microbubble flotation column, a positive flotation agent is added, and a first positive flotation is performed to obtain a third slurry; the third slurry is pumped into the fourth cyclone-static microbubble flotation column, and the same positive flotation agent as the first positive flotation is added, and a second positive flotation is performed to obtain phosphogypsum concentrate;

[0029] Step 5: The phosphogypsum concentrate obtained after two reverse flotation and two forward flotation treatments is pumped into a plate and frame filter press for dehydration. After dehydration, the concentrate is dried to obtain whitened and impurity-free phosphogypsum.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] 1. The phosphogypsum reverse flotation whitening and impurity removal agent provided by the present invention is suitable for strong acid environment, has high selectivity for organic carbon in acidic environment, and can capture black organic carbon, iron impurities and silicon dioxide at the same time; it has the performance of a frother, does not need to add an additional frother, has the advantages of stable performance, strong capture ability, fast flotation speed, low dosage, etc.; at the same time, the present invention adopts a cyclone-static microbubble flotation column as a pilot flotation device (phosphogypsum processing capacity 3600 tons / year), which is consistent with the particle size distribution characteristics of phosphogypsum ( The fine-grained minerals under the 400-mesh sieve account for more than 25% and have a finer particle size; the coarse-grained minerals on the 100-mesh sieve account for about 20%) are more matched, and have better sorting effects than traditional flotation machines. The phosphogypsum is subjected to two reverse flotations using a cyclone-static microbubble flotation column, and the whiteness of the phosphogypsum is increased from 35% to 64.5%, and the grade (calculated as CaSO4.2H2O) is increased from 90% to 93%, the iron impurity removal rate is more than 70%, and the silicon dioxide removal rate is about 45%. The cyclone-static microbubble flotation column is used to perform "two reverse and two positive" flotation on phosphogypsum, and the whiteness is increased from 35% to 74.5%, which is significantly improved, much higher than the whiteness improvement effect of two reverse and two positive flotations using a traditional flotation machine (such as from 35% to 58.2%).

[0032] 2. The reverse flotation whitening and impurity removal agent for phosphogypsum provided by the present invention can be directly used for the flotation whitening and impurity removal of phosphogypsum. After two reverse and two positive flotation processes, the whiteness can be increased to 74.5%. The black organic carbon, iron impurities and silicon dioxide in the phosphogypsum are removed simultaneously in the same flotation process. The phosphogypsum after flotation purification meets the first-class standard in GB / T 23456-2018 "Phosphogypsum", and can be directly used for the preparation of β-gypsum and anhydrous gypsum, etc.

[0033] 3. The phosphogypsum in the present invention is subjected to "two reverse and two positive" flotation treatment to obtain high-quality phosphogypsum with a whiteness of 74.5% and a purity of 98.2%. The whiteness of β-gypsum prepared from the phosphogypsum can reach more than 80%. Due to the removal of organic carbon, the problem of floating black (organic carbon) on the surface of β-gypsum when used as self-leveling is solved, thereby improving the performance of β-gypsum products.

[0034] 4. The present invention obtains phosphogypsum concentrate with a whiteness of 74.5% through "two reverse and two positive" flotation of phosphogypsum. When the content of iron impurities (in terms of Fe2O3) in the original gypsum is 0.38% (quantitative analysis by XRF line), after reverse flotation, the iron impurities are reduced to 0.1% (quantitative analysis by XRF line). The whiteness of anhydrous gypsum prepared from the phosphogypsum is about 82% (the original gypsum is reddish due to the iron impurities contained in it, and the whiteness is only about 43%), which solves the problem of redness of the original gypsum after being prepared into anhydrous gypsum, and broadens the application range of phosphogypsum products.

[0035] 5. The phosphogypsum in the present invention is subjected to "two reverse and two positive" flotation treatment to obtain high-quality phosphogypsum with a whiteness of 74.5% and a purity of 98.2%, which improves the physical and chemical properties of the phosphogypsum, specifically in terms of the improvement of whiteness and purity, and the effective removal of organic carbon, iron impurities and silicon dioxide. The back-end application scope of phosphogypsum is broadened, specifically in terms of the removal of iron impurities, the solution to the problem of high-temperature anhydrous gypsum turning red, and the application scope of anhydrous gypsum is greatly expanded. The improvement of whiteness expands the use of phosphogypsum to the fields of gypsum lines, ceramic molds, putty powder, etc.

[0036] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings are only for the purpose of illustrating particular embodiments and are not to be construed as limiting the invention.

[0038] Figure 1 This is a process flow chart of the "two-reverse" flotation of phosphogypsum of the present invention;

[0039] Figure 2 A schematic diagram of a cyclone-static microbubble flotation column used in the present invention;

[0040] Figure 3 A schematic diagram of the flotation process of the cyclone-static microbubble flotation column used in the present invention;

[0041] Figure 4 This is a comparison diagram of phosphogypsum before and after whitening and impurity removal treatment in Example 1 of the present invention;

[0042] Figure 5 A comparison chart showing whether black floating occurs during self-leveling of β-building gypsum prepared from phosphogypsum after flotation treatment and original phosphogypsum in Example 1 of the present invention;

[0043] Figure 6 This is a comparison chart of the anhydrous gypsum prepared from the phosphogypsum after flotation treatment in Example 1 of the present invention and the original phosphogypsum.

[0044] Figure 7 This is a comparison diagram of the XRD spectra of the phosphogypsum ore and concentrate in Example 4 of the present invention;

[0045] Figure 8 The figure is a process flow chart of the "two reverse and two positive" flotation of phosphogypsum according to the present invention.

[0046] 1- raw phosphogypsum from Example 1 of the present invention; 2- phosphogypsum treated with reverse flotation agent from Example 1 of the present invention; 3- beta building gypsum prepared from raw phosphogypsum from Example 1 of the present invention has black floating phenomenon during self-leveling; 4- beta building gypsum prepared from phosphogypsum treated with reverse flotation agent from Example 1 of the present invention has no black floating phenomenon during self-leveling; 5- anhydrous gypsum prepared from raw phosphogypsum from Example 1 of the present invention; 6- anhydrous gypsum prepared from phosphogypsum treated with reverse flotation agent from Example 1 of the present invention. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0048] The invention provides a phosphogypsum reverse flotation whitening and impurity removal agent, wherein the agent comprises tributyl phosphate, terpineol, a fatty alkyl (R) carbon chain length of C 12 ~C 20 The carbon chain length of the fatty primary amine (R-NH2) and fatty alkyl (R) is C 12 ~C 20 A compound agent of dimethyl tertiary amine (RN(CH3)2).

[0049] At present, the flotation collector for whitening and removing impurities of phosphogypsum has low selectivity for organic carbon, poor acid resistance, unobvious whitening effect, and weak ability to remove iron impurities in phosphogypsum. Compared with the prior art, the reverse flotation whitening and impurity removal agent of the present invention has good acid resistance and can capture black organic carbon, iron impurities and silica at the same time; it has stable performance, strong collecting capacity, fast flotation speed and low dosage, which solves the problems of poor acid resistance, low selectivity for organic carbon, poor whitening effect and weak ability to remove iron impurities in phosphogypsum in the prior art.

[0050] Specifically, the fatty primary amine (R-NH2) in the reverse flotation agent is one or more of dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine; the dimethyl tertiary amine (RN(CH3)2) in the reverse flotation agent is one or more of dodecyldimethyltertiary amine, tetradecyldimethyltertiary amine, hexadecyldimethyltertiary amine, and octadecyldimethyltertiary amine.

[0051] Specifically, the raw material composition of the reverse flotation agent is calculated by mass percentage as follows: tributyl phosphate: 5% to 15%; terpineol: 5% to 15%; the carbon chain length of the fatty alkyl (R) is C 12 ~C 20 Fatty primary amine (R-NH2) in the range of 30% to 60%; fatty alkyl (R) carbon chain length is C 12 ~C 20Range of dimethyl tertiary amine (RN(CH3)2): 20% to 40%.

[0052] It should be noted that the components and contents of the present invention can give full play to the synergistic enhancement effect between the components. The present invention adopts tributyl phosphate, terpineol, and fatty alkyl (R) carbon chain length in the range of C 12 ~C 20 The carbon chain length of fatty primary amine (R-NH2) and fatty alkyl (R) is within the range of C 12 ~C 20 The reverse flotation whitening and impurity removal agent for phosphogypsum is compounded with dimethyl tertiary amine (RN(CH3)2) within a certain range. Fatty primary amines and dimethyl tertiary amines are effective collectors, which remove silica from phosphogypsum through electrostatic adsorption and have weak hydrogen bonding. The addition of pine oil alcohol is beneficial to reduce the surface tension of the flotation pulp, produce more fine and uniform foams, and improve the hydrophobicity of fine mud-level impurities (organic carbon, iron impurities, silica and other impurity particles are finer) in phosphogypsum, which is beneficial for collectors such as primary amines and tertiary amines to capture and remove impurities. At the same time, the activated dimethyl tertiary amine has the function of a foaming agent, and pine oil alcohol has the effect of stabilizing its foam. Dimethyl tertiary amine is an emulsifier for pine oil alcohol. As a dispersing carrier of dimethyl tertiary amine, its own hydrophobicity can improve the hydrophobic ability of the hydrophobic end of dimethyl tertiary amine, and synergistically improve the reverse flotation agent's ability to capture organic carbon, iron impurities, silica and other impurities. Dimethyl tertiary amine is not only the main collector, but also has the function of a foaming agent and good acid resistance. At the same time, its good emulsifying effect can make fatty primary amines and pinene alcohol have better dispersion. The addition of tributyl phosphate can adjust the excessive foaming behavior of dimethyl tertiary amine and improve the fluidity of the foam system. Preventing excessive foaming can reduce the entrainment of calcium sulfate dihydrate in the foam system and improve the yield of phosphogypsum concentrate.

[0053] The present invention also provides a method for preparing a phosphogypsum reverse flotation whitening and impurity removal agent, which is used to prepare the phosphogypsum reverse flotation whitening and impurity removal agent, comprising:

[0054] Tributyl phosphate, pineneol and fatty primary amine are added to dimethyl tertiary amine solution, and mechanically stirred to obtain a reverse flotation agent solution system; during the stirring and homogenization of the reverse flotation agent solution system, a certain amount of water is added to adjust the mass fraction of the reverse flotation agent solution.

[0055] Specifically, the mass fraction of dimethyl tertiary amine solution is 30-40%. Before use, the dimethyl tertiary amine solution needs to be activated. Preferably, the activator selected is a mixed solution of acetic acid and hydrogen peroxide in a mass ratio of 0.1:1. Acetic acid and hydrogen peroxide are mechanically stirred and mixed evenly at a mass ratio of 0.1:1, and then slowly added dropwise to a dimethyl tertiary amine (RN(CH3)2) aqueous solution of the same mass as hydrogen peroxide (the mass fraction of dimethyl tertiary amine is 30%), and the reaction temperature is set to 70°C. In this process, the tertiary amine is activated to an amine oxide with good foaming properties. The reaction formula is as follows:

[0056]

[0057] First, acetic acid and hydrogen peroxide are stirred and mixed, and then added to the dimethyl tertiary amine aqueous solution, and the three substances cannot be mixed at the same time. In this reaction, acetic acid is used as a catalyst for the reaction system. Acetic acid and hydrogen peroxide are first mixed. Acetic acid can provide a weak acid environment for hydrogen peroxide to prevent its decomposition. In this process, peracetic acid (actually catalytic) is generated, and it can also avoid direct contact between acetic acid and dimethyl tertiary amine, resulting in the protonation of dimethyl tertiary amine and inability to be oxidized. The mixing time of acetic acid and hydrogen peroxide is 30-40 minutes. During this time period, the two are mixed evenly and fully reacted to generate a certain amount of peracetic acid as a catalyst for the oxidation of dimethyl tertiary amine. Then slowly and evenly add it to the dimethyl tertiary amine aqueous solution system to react for 3-4 hours to ensure that the dimethyl tertiary amine is activated and amine oxide is generated.

[0058] Specifically, the stirring time is 1-2 hours. The mass fraction of the reverse flotation agent is 5-7%. A lower mass fraction can make the reverse flotation agent disperse faster when added to the ore pulp system and better play the collection effect.

[0059] The present invention also provides a phosphogypsum reverse flotation whitening and impurity removal process, which uses the above-mentioned phosphogypsum reverse flotation whitening and impurity removal agent, and comprises the following steps:

[0060] Step 1: connect two cyclone-static microbubble flotation columns in series;

[0061] Step 2: transporting the phosphogypsum to be treated to a slurry mixing tank for slurry mixing to obtain phosphogypsum slurry;

[0062] Step 3: The phosphogypsum slurry in the slurry mixing tank is pumped into the first cyclone-static microbubble flotation column, and a reverse flotation agent is added to perform the first reverse flotation to obtain the first slurry; the first slurry is pumped into the second cyclone-static microbubble flotation column, and the reverse flotation agent same as the first reverse flotation is added to perform the second reverse flotation to obtain the phosphogypsum concentrate;

[0063] Step 4: The phosphogypsum concentrate obtained after two reverse flotation treatments is pumped into a plate and frame filter press for dehydration. After dehydration, the concentrate is dried to obtain whitened and impurity-free phosphogypsum.

[0064] Specifically, the main components of solid waste phosphogypsum produced in the phosphorus chemical industry are below 200 mesh (75μm), and the 400 mesh (38μm) sieve accounts for more than 25%, with a relatively fine particle size. Exemplary, the particle size distribution of the phosphogypsum to be treated: the fine-grained minerals under the 400 mesh sieve account for more than 25%, with a relatively low whiteness of about 10%, containing a large amount of organic matter and iron impurities; the coarse-grained minerals on the 100 mesh sieve account for about 20%, with a relatively low whiteness of about 20%, containing a large amount of siliceous impurities and iron impurities.

[0065] When flotation columns are used for separation, according to the particle size distribution characteristics and impurity distribution of phosphogypsum, the phosphogypsum does not need to be ground and can be directly put into flotation columns for separation. When the cyclone-static microbubble flotation column is used as the pilot flotation equipment, the phosphogypsum processing capacity is 3,600 tons / year.

[0066] The present invention adopts a pilot flotation system of a cyclone-static microbubble flotation column, and uses the cyclone-static microbubble flotation column to perform two reverse and two positive flotations on phosphogypsum. The pilot flotation system includes three parts: a pulping system, a flotation column flotation zone, and a dehydration zone (see attached Figure 3 ), wherein the flotation column flotation zone includes a plurality of cyclone-static microbubble flotation columns, and the cyclone-static microbubble flotation columns include an aeration regulating valve, a foam collecting tank, a microbubble generator, a circulating middling outlet pipe, a tailings outlet pipe, a cyclone zone and a static flotation zone (see attached Figure 2 ), the gas volume regulating valve is used to adjust the gas volume, the foam collecting tank is used to collect foam, the microbubble generator is used to generate microbubbles, the mixed mineralization pipe is used to mineralize the phosphogypsum with microbubbles, the circulating middling ore outlet pipe is used to output the middling ore, the tailings outlet pipe is used to output the tailings, the cyclone area is used to mineralize and separate the phosphogypsum, and the static flotation area is used to perform static flotation.

[0067] Cyclone-static microbubble flotation column flotation process Figure 2 As shown, the cyclone-static microbubble flotation column separation method includes three parts: column flotation, cyclone separation, and tube flow mineralization.

[0068] Column flotation is carried out in the static flotation zone located in the upper area of ​​the entire column. It adopts the flotation principle of countercurrent collision mineralization to achieve the separation of fine materials in a low-turbulence static separation environment, and plays a role in roughing and concentrating in the entire column flotation method; cyclone separation is carried out in the cyclone zone located below the static flotation zone. Feeding is carried out from the top of the static flotation zone. After the microbubbles are generated by the microbubble generator, they enter the static flotation zone from the bottom of the static flotation zone. After column flotation, the materials enter the cyclone zone below the static flotation zone for cyclone separation. The column flotation and cyclone separation carried out from top to bottom constitute the main body of the cyclone-static microbubble flotation column separation method, which has a re-selection effect on the middlings and circulating middlings that have been separated by column separation. Under the action of the cyclone force field, the two parts of the middlings are separated according to density, and the low-density materials (including most of the bubbles and mineralized bubbles) gather in the middle of the cyclone separation section and enter the column separation section upward, and undergo the concentrating process of column separation again. Therefore, cyclone flotation not only provides an efficient mineralization method, but also greatly reduces the lower limit of flotation particle size and greatly improves the flotation speed. As a supplement to surface flotation, the cyclone separation section strengthens sorting and recovery. Pipe flow mineralization utilizes the jet principle. By introducing gas and crushing into bubbles, a gas-solid-liquid three-phase system of circulating ore is formed in the pipe flow and highly turbulent mineralization is achieved. The cyclone-static microbubble flotation column can produce nano-sized bubbles and microbubbles below 200μm. Compared with the traditional flotation machine that produces bubbles in the range of 0.1 to 1mm, it is more suitable for the flotation of fine-grained phosphogypsum.

[0069] Specifically, in step 2, the phosphogypsum is newly discharged phosphogypsum from a phosphating plant, has a pH of 1 to 3, has a storage time of 0 to 6 months, has a slurry mass concentration of 30% to 40%, and is at room temperature;

[0070] Ordinary process water and phosphogypsum are used for slurry adjustment. According to the weight of the phosphogypsum to be treated, process water is added in a certain ratio to ensure that the prepared slurry concentration is 30% to 40%. Under this concentration range, the dispersibility of phosphogypsum is good, and the collection ability and separation of the reagent are better; according to the test, when the pH value of the slurry is 1 to 3, the reverse flotation impurity removal and whitening effect is better, and the reverse flotation concentrate yield is higher. Phosphogypsum comes from the phosphoric acid preparation process. The phosphogypsum itself contains free acid (phosphoric acid and sulfuric acid, etc.). The original pH value of the phosphogypsum slurry is between 2.0 and 2.5. After the slurry adjustment is completed, the pH value of the slurry can meet the pH range requirements of the reverse flotation effect. Therefore, the flotation process of the present invention does not need to adjust the pH value of the slurry.

[0071] Specifically, in step 3, the amount of the first reverse flotation reagent is 60g / t to 160g / t, and the amount of the second reverse flotation reagent is 0g / t to 100g / t. If the amount of the first reverse flotation reagent is less than 60g / t, the impurity removal effect is not good, and the whiteness increase is not large. Because the first reverse flotation reagent remains, the second reverse flotation reagent is reduced. The total amount of the two reverse flotation reagents is not higher than 260g / t. If the total amount is greater than 260g / t, the whiteness of the phosphogypsum flotation product remains almost unchanged, and further increasing the amount of reverse flotation reagents will increase the cost. The first reverse flotation can increase the whiteness of phosphogypsum from 35% to 57%, and the second reverse flotation can increase the whiteness from 57% to 63%. Compared with the existing flotation agents for removing organic carbon from phosphogypsum, this flotation agent has a higher selectivity for organic carbon and a smaller dosage, less than 260g / t phosphogypsum. At the same time, it can remove iron impurities in phosphogypsum more thoroughly and can remove more than 70% of the iron impurities in phosphogypsum.

[0072] Specifically, in step 3, the total residence time of the slurry in the first reverse flotation and the second reverse flotation is 10 to 15 minutes. Too short a residence time will result in low tailings (foam) yield and reduced concentrate quality, while too long a residence time will result in high tailings (foam) yield and too low concentrate yield. Preferably, in the reverse flotation section, the total residence time of the slurry is 15 minutes.

[0073] Specifically, in step 4, the dehydration equipment is a plate-frame filter press system, and the phosphogypsum is dried after dehydration. The drying temperature of the phosphogypsum is 40-50° C. Within this temperature range, only free water can be removed, and the crystal water of the phosphogypsum will not be lost. The whiteness of the dried phosphogypsum is measured by a blue light whiteness meter. Preferably, the drying temperature of the phosphogypsum is 45° C.

[0074] The present invention also provides a phosphogypsum whitening and impurity removal process, which uses the above-mentioned phosphogypsum reverse flotation whitening and impurity removal agent, and comprises the following steps:

[0075] Step 1: connect four cyclone-static microbubble flotation columns in series;

[0076] Step 2: transporting the phosphogypsum to be treated to a slurry mixing tank for slurry mixing to obtain phosphogypsum slurry;

[0077] Step 3: The phosphogypsum slurry in the slurry mixing tank is pumped into the first cyclone-static microbubble flotation column, and a reverse flotation agent is added to perform the first reverse flotation to obtain the first slurry; the first slurry is pumped into the second cyclone-static microbubble flotation column, and the reverse flotation agent same as that of the first reverse flotation is added to perform the second reverse flotation to obtain the second slurry;

[0078] Step 4: The second slurry is pumped into the third cyclone-static microbubble flotation column, a positive flotation agent is added, and a first positive flotation is performed to obtain a third slurry; the third slurry is pumped into the fourth cyclone-static microbubble flotation column, and the same positive flotation agent as the first positive flotation is added, and a second positive flotation is performed to obtain phosphogypsum concentrate;

[0079] Step 5: The phosphogypsum concentrate obtained after two reverse flotation and two forward flotation treatments is pumped into a plate and frame filter press for dehydration. After dehydration, the concentrate is dried to obtain whitened and impurity-free phosphogypsum.

[0080] Specifically, in steps 1-3, the flotation equipment and process parameters used are the same as those of the above-mentioned "two-reverse" flotation process.

[0081] Specifically, in step 4, the positive flotation reagent is a fatty alkyl (R) carbon chain length of C 12 ~C 20 The raw material composition of the positive flotation reagent is calculated by mass percentage as follows: the carbon chain length of the fatty alkyl (R) is C 12 ~C 20 The alkyl propyl ether amine (RO-CH2CH2CH2NH2) of the positive flotation agent is 30% to 60%; dodecylamine: 39.6% to 63.3%; acetic acid solution with a mass fraction of 0.5% to 5.0%: 10.4% to 16.7%. The alkyl propyl ether amine (RO-CH2CH2CH2NH2) in the positive flotation agent is one or more of dodecyl propyl ether amine, tetradecyl propyl ether amine, hexadecyl propyl ether amine, and octadecyl propyl ether amine. The positive flotation agent can remove silicon dioxide that mainly affects the purity of phosphogypsum and further remove impurities such as iron impurities, increase the purity of phosphogypsum, and further improve the whiteness of phosphogypsum.

[0082] In step 4, the dosage of the first positive flotation reagent is 160g / t to 260g / t, and the dosage of the second positive flotation reagent is 0g / t to 100g / t. The dosage of the first positive flotation reagent is less than 160g / t, which cannot effectively capture and float all the phosphogypsum, resulting in a low final concentrate yield of phosphogypsum; due to the residual reagent of the first positive flotation, the second positive flotation reagent is reduced. The total dosage of the two positive flotation reagents is not higher than 360g / t. Excessive dosage of the positive flotation reagent will lead to excessive concentrate yield, reduced quality and increased cost. The first positive flotation can increase the whiteness of phosphogypsum from 63% to 70.5%, and the second reverse flotation can increase the whiteness from 70.5% to 74.5%. The positive flotation reagent of the present invention has strong collecting ability for phosphogypsum, high selectivity, and small dosage, which is less than 360g / t phosphogypsum. At the same time, the silicon dioxide and iron impurities in the phosphogypsum are removed more thoroughly, and more than 80% of the silicon impurities in the phosphogypsum can be removed and the iron impurity content in the phosphogypsum can be further reduced. The purity of the phosphogypsum (measured in terms of CaSO4.2H2O content) is increased from 93% after reverse flotation to about 98.2%.

[0083] Specifically, in step 4, the total residence time of the slurry in the first positive flotation and the second positive flotation is 10 to 15 minutes. If the residence time is too short, the concentrate (foam) yield will be too low, and if the residence time is too long, the concentrate (foam) yield will be too high and the concentrate quality will decrease. Preferably, in the positive flotation section, the total residence time of the slurry is 15 minutes.

[0084] Specifically, in step 5, the dehydration equipment is a plate-frame filter press system, and the phosphogypsum is dried after dehydration. The drying temperature of the phosphogypsum is 40-50° C. Within this temperature range, only free water can be removed, and the crystal water of the phosphogypsum will not be lost. The whiteness of the dried phosphogypsum is measured by a blue light whiteness meter. Preferably, the drying temperature of the phosphogypsum is 45° C.

[0085] The phosphogypsum treated with the phosphogypsum reverse flotation whitening and impurity removal agent of the present invention is treated by "two reverse" flotation, and the whiteness of the phosphogypsum concentrate is increased to 64.5% (dried at 45°C), and the grade (calculated as CaSO4.2H2O) is increased to 93%. After "two reverse and two positive" flotation treatment, the whiteness of the phosphogypsum concentrate is increased to 74.5% (dried at 45°C), and the grade (calculated as CaSO4.2H2O) is increased to 98.2%. The whiteness of beta gypsum prepared by using the phosphogypsum can reach more than 80%. Due to the removal of organic matter, the problem of floating black (organic carbon) on the surface of beta gypsum when used as self-leveling is solved, and the performance of beta gypsum products is improved. The whiteness of anhydrous gypsum prepared by using the phosphogypsum is about 82% (the original gypsum contains iron impurities, so the anhydrous gypsum prepared is red and the whiteness is only about 43%), which solves the problem that the original gypsum turns red after being prepared into anhydrous gypsum and broadens the application range of phosphogypsum products. Specific embodiments

[0087] In Examples 1-3, without changing the method for preparing the reverse flotation impurity removal and whitening agent, only the mass percentages of the raw material components were changed.

[0088] In the following examples, the phosphogypsum used is all phosphogypsum produced as a by-product of a phosphate ore in Guizhou, with a storage time of 0 to 6 months, a whiteness of 35%, a pH of 1 to 3, and a phosphogypsum purity (calculated as CaSO4.2H2O) of 90%.

[0089] In Examples 1-3, the flotation process used is two reverse flotation. In order to prove the influence of the quality change of the raw material components of the reverse flotation impurity removal and whitening agent in the examples on the flotation product index of phosphogypsum, the flotation test was carried out on the same phosphogypsum in the examples, and the flotation process was controlled to be completely consistent. Specifically, during the flotation process, the pulp concentration was 35%, the amount of the first reverse flotation agent was 100g / t, and the amount of the second reverse flotation agent was 30g / t.

[0090] In Examples 1-3, the whiteness of the phosphogypsum was tested after drying, and the whiteness was measured using blue light. The drying temperature of the phosphogypsum was 45°C.

[0091] Since organic carbon and iron impurities in phosphogypsum are the main impurities affecting the whiteness of phosphogypsum, the whiteness and CaSO4·2H2O content of phosphogypsum are taken as evaluation indicators to illustrate the performance of reverse flotation reagents in removing impurities and increasing whiteness.

[0092] Example 1

[0093] In this embodiment, the reverse flotation reagent is a compound reagent of tributyl phosphate, pineol, dodecylamine, and tetradecyl dimethyl tertiary amine, and the mass percentages of the raw materials of the reverse flotation reagent are: 10% tributyl phosphate, 10% pineol, 50% dodecylamine, and 30% tetradecyl dimethyl tertiary amine;

[0094] The test results show that the whiteness of the phosphogypsum ore is 35% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is 90%, the SiO2 content is 3.98%, and the iron impurities (calculated as Fe2O3) are 0.38%. After two reverse flotation, the whiteness of the phosphogypsum concentrate is increased to 63% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is increased to 93%, the SiO2 content is reduced to 2.1%, the iron impurities (calculated as Fe2O3) are reduced to 0.1%, and the yield of the phosphogypsum concentrate is 89%.

[0095] Example 2

[0096] In this embodiment, the reverse flotation reagent is a compound reagent of tributyl phosphate, pineol, dodecylamine, and tetradecyl dimethyl tertiary amine, and the mass percentages of the raw materials of the reverse flotation reagent are: 10% tributyl phosphate, 10% pineol, 40% dodecylamine, and 40% tetradecyl dimethyl tertiary amine;

[0097] The test results show that the whiteness of the phosphogypsum concentrate is increased to 64% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is increased to 92%, and the yield of the phosphogypsum concentrate is 82%.

[0098] Example 3

[0099] In this embodiment, the reverse flotation reagent is a compound reagent of tributyl phosphate, pineol, dodecylamine, and tetradecyl dimethyl tertiary amine, and the mass percentages of the raw materials of the reverse flotation reagent are: 15% tributyl phosphate, 15% pineol, 30% dodecylamine, and 40% tetradecyl dimethyl tertiary amine;

[0100] The test results show that the whiteness of the phosphogypsum concentrate is 64.5% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is 91.5%, and the yield of the phosphogypsum concentrate is 79%.

[0101] Example 4

[0102] This embodiment provides a process for whitening and removing impurities from phosphogypsum, and the phosphogypsum used is the same as that in Embodiments 1-3.

[0103] In this embodiment, the reverse flotation reagent is a compound reagent of tributyl phosphate, pineol, dodecylamine and tetradecyldimethyl tertiary amine, and the mass percentages of the raw materials of the reverse flotation reagent are: 10% tributyl phosphate, 10% pineol, 50% dodecylamine, and 30% tetradecyldimethyl tertiary amine; the positive flotation reagent is a compound reagent of dodecyl propyl ether amine, dodecylamine, and 0.5% to 5.0% acetic acid solution by mass, and the mass percentages of the raw materials of the positive flotation reagent are: 40% dodecyl propyl ether amine, 47.5% dodecylamine, and 12.5% ​​acetic acid solution with a mass fraction of 0.5% to 5.0%.

[0104] Step 1: four cyclone-static microbubble flotation columns are connected in series, the first two flotation columns are used for reverse flotation of phosphogypsum, and the last two flotation columns are used for positive flotation of phosphogypsum;

[0105] Step 2: The phosphogypsum to be treated is conveyed to a slurry mixing tank through a belt, and slurry is mixed with ordinary process water to adjust the slurry mass concentration to 35%;

[0106] Step 3: Reverse flotation section: the phosphogypsum slurry in the slurry mixing tank is pumped into the first cyclone-static microbubble flotation column, and the reverse flotation agent is added to carry out the first reverse flotation, and the agent dosage is 100g / t. The phosphogypsum slurry after the first reverse flotation is pumped into the second cyclone-static microbubble flotation column, and the reverse flotation agent is added to carry out the second reverse flotation, and the agent dosage is 30 / t; the total residence time of the slurry for the two reverse flotation is 15min.

[0107] Step 4: Direct flotation section: The phosphogypsum concentrate after the second reverse flotation is pumped into the third cyclone-static microbubble flotation column, and positive flotation reagent is added to carry out the first positive flotation. The reagent dosage is 190g / t. The phosphogypsum slurry after the first positive flotation is pumped into the fourth cyclone-static microbubble flotation column for the second positive flotation. The amount of positive flotation reagent added is 30g / t. The total residence time of the slurry for the two positive flotations is 15min.

[0108] Step 5: Filtration section: The phosphogypsum concentrate obtained after the second positive flotation treatment is pumped into the plate and frame filtration and dehydration equipment to complete the dehydration, and then dried at 45°C to obtain the whitened and impurity-free phosphogypsum.

[0109] The test results show that the whiteness of the phosphogypsum ore is 35% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is 90%, the SiO2 content is 3.98%, and the iron impurities (calculated as Fe2O3) are 0.38%. After four flotations of two reverse and two positive flotations, the whiteness of the phosphogypsum concentrate is increased to 74.5% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is increased to 98.2%, the SiO2 content is reduced to 0.5%, the iron impurities (calculated as Fe2O3) are reduced to 0.06%, the yield of the phosphogypsum concentrate is 75%, and the recovery rate (calculated as CaSO4.2H2O) is 81.83%.

[0110] Example 5-1

[0111] In step 2, the phosphogypsum to be treated is conveyed to a re-slurry tank by a belt, and slurry is adjusted with ordinary process water, and the slurry mass concentration is 30%; the remaining process steps and parameters are the same as those in Example 4.

[0112] The test results show that the whiteness of the phosphogypsum concentrate is increased to 72.6% (dried at 45°C), the phosphogypsum grade (calculated as CaSO4.2H2O) is increased from 90% to 98%, the concentrate yield is 65%, and the recovery rate (calculated as CaSO4.2H2O) is 78.77%.

[0113] Example 5-2

[0114] In step 2, the phosphogypsum to be treated is conveyed to a slurry mixing tank by a belt, and slurry is mixed with ordinary process water, and the slurry mass concentration is 33%; the remaining process steps and parameters are the same as those in Example 4.

[0115] The test results show that the whiteness of the phosphogypsum concentrate increased to 73.5% (dried at 45°C), the phosphogypsum grade (calculated as CaSO4.2H2O) increased from 90% to 97.5%, the concentrate yield was 67%, and the recovery rate (calculated as CaSO4.2H2O) was 79.58%.

[0116] Example 5-3

[0117] In step 2, the phosphogypsum to be treated is conveyed to a re-slurry tank by a belt, and slurry is adjusted with ordinary process water, and the slurry concentration is 40%; the remaining process steps and parameters are the same as those in Example 4.

[0118] The test results show that the whiteness of the phosphogypsum concentrate increased to 73.7% (dried at 45°C), the phosphogypsum grade (calculated as CaSO4.2H2O) increased from 90% to 97.5%, the concentrate yield was 76%, and the recovery rate (calculated as CaSO4.2H2O) was 80.64%.

[0119] Example 6-1

[0120] In step 3, the reverse flotation section, the total residence time of the two reverse flotation pulps is 10 minutes; in step 4, the forward flotation section, the total residence time of the two forward flotation pulps is 10 minutes. The remaining process steps and parameters are the same as those in Example 4.

[0121] The test results show that the whiteness of the phosphogypsum concentrate increased to 72.7% (dried at 45°C), the phosphogypsum grade (calculated as CaSO4.2H2O) increased from 90% to 97.8%, the concentrate yield was 68%, and the recovery rate (calculated as CaSO4.2H2O) was 71.78%.

[0122] Example 6-2

[0123] In step 3, the reverse flotation section, the total residence time of the two reverse flotation pulps is 13 minutes; in step 4, the forward flotation section, the total residence time of the two forward flotation pulps is 13 minutes. The remaining process steps and parameters are the same as those in Example 4.

[0124] The test results show that the whiteness of the phosphogypsum concentrate increased to 73.8% (dried at 45°C), the phosphogypsum grade (calculated as CaSO4.2H2O) increased from 90% to 97.8%, the concentrate yield was 69%, and the recovery rate (calculated as CaSO4.2H2O) was 75.56%.

[0125] Example 7-1

[0126] In this embodiment, the first reverse flotation reagent dosage is 60g / t, and the second reverse flotation reagent dosage is 0g / t; the first positive flotation reagent dosage is 160g / t, and the second positive flotation reagent dosage is 0g / t; the remaining process steps and parameters are the same as those in Example 4.

[0127] The test results show that the drying whiteness of phosphogypsum before flotation is 35%, and the drying whiteness of phosphogypsum concentrate after flotation is 71.6%. The purity of phosphogypsum after flotation (calculated as CaSO4.2H2O) increases from 90% to 97.3%, the yield of phosphogypsum concentrate is 73%, and the recovery rate (calculated as CaSO4.2H2O) is 80.58%.

[0128] Example 7-2

[0129] In this embodiment, the first reverse flotation reagent dosage is 160g / t, and the second reverse flotation reagent dosage is 100g / t; the first positive flotation reagent dosage is 260g / t, and the second positive flotation reagent dosage is 100g / t; the remaining process steps and parameters are the same as those in Example 4.

[0130] The test results show that the drying whiteness of phosphogypsum before flotation is 35%, and the drying whiteness of phosphogypsum concentrate after flotation is 72.8%. The purity of phosphogypsum after flotation (calculated as CaSO4.2H2O) increases from 90% to 97.6%, the yield of phosphogypsum concentrate is 74%, and the recovery rate (calculated as CaSO4.2H2O) is 80.89%.

[0131] Example 8-1

[0132] Compared with Example 4, this example changes the mass percentage of the raw material components of the flotation reagent to obtain different flotation indicators.

[0133] In step 3, the reverse flotation reagent is a compound reagent of tributyl phosphate, pineol, dodecylamine and tetradecyl dimethyl tertiary amine, and the mass percentages of the reverse flotation reagent raw materials are: 15% tributyl phosphate, 5% pineol, 50% dodecylamine, and 30% tetradecyl dimethyl tertiary amine; the first reverse flotation reagent dosage is 100g / t, and the second reverse flotation reagent dosage is 30g / t.

[0134] In step 4, the positive flotation reagent is a compound reagent of dodecyl propyl ether amine, dodecylamine, and 0.5% to 5.0% acetic acid solution by mass. The mass percentages of the positive flotation reagent raw materials are: 40% dodecyl propyl ether amine, 47.5% dodecylamine, and 12.5% ​​acetic acid solution by mass fraction of 0.5% to 5.0% respectively; the first positive flotation reagent dosage is 190 g / t, and the second positive flotation reagent dosage is 30 g / t.

[0135] The remaining process steps and parameters are the same as those in Example 4.

[0136] The test results show that the whiteness of the phosphogypsum ore is 35% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is 90%, the SiO2 content is 3.98%, and the iron impurities (calculated as Fe2O3) are 0.38%. After flotation, the whiteness of the phosphogypsum concentrate is increased to 72.7% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is increased to 96.8%, the SiO2 content is reduced to 0.5%, the iron impurities (calculated as Fe2O3) are reduced to 0.09%, the yield of the phosphogypsum concentrate is 75.3%, and the recovery rate (calculated as CaSO4.2H2O) is 80.99%.

[0137] Example 8-2

[0138] In step 3, the reverse flotation reagent is a compound reagent of tributyl phosphate, pineol, dodecylamine and tetradecyl dimethyl tertiary amine, and the mass percentages of the reverse flotation reagent raw materials are: 15% tributyl phosphate, 15% pineol, 30% dodecylamine, and 40% tetradecyl dimethyl tertiary amine; the first reverse flotation reagent dosage is 100g / t, and the second reverse flotation reagent dosage is 30g / t.

[0139] In step 4, the positive flotation reagent is a compound reagent of dodecyl propyl ether amine, dodecylamine, and 0.5% to 5.0% acetic acid solution by mass. The mass percentages of the positive flotation reagent raw materials are: 40% dodecyl propyl ether amine, 47.5% dodecylamine, and 12.5% ​​acetic acid solution by mass fraction of 0.5% to 5.0% respectively; the first positive flotation reagent dosage is 190 g / t, and the second positive flotation reagent dosage is 30 g / t.

[0140] The remaining process steps and parameters are the same as those in Example 4.

[0141] The test results show that the whiteness of the phosphogypsum ore is 35% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is 90%, the SiO2 content is 3.98%, and the iron impurities (calculated as Fe2O3) are 0.38%. After flotation, the whiteness of the phosphogypsum concentrate is increased to 72.5% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is increased to 96.5%, the SiO2 content is reduced to 0.55%, the iron impurities (calculated as Fe2O3) are reduced to 0.05%, the yield of the phosphogypsum concentrate is 76.8%, and the recovery rate (calculated as CaSO4.2H2O) is 82.35%.

[0142] Example 8-3

[0143] In step 3, the reverse flotation reagent is a compound reagent of tributyl phosphate, pineol, dodecylamine and tetradecyl dimethyl tertiary amine, and the mass percentages of the reverse flotation reagent raw materials are: 10% tributyl phosphate, 10% pineol, 50% dodecylamine, and 30% tetradecyl dimethyl tertiary amine; the first reverse flotation reagent dosage is 100g / t, and the second reverse flotation reagent dosage is 30g / t.

[0144] In step 4, the positive flotation reagent is a compound reagent of dodecyl propyl ether amine, dodecylamine, and 0.5% to 5.0% acetic acid solution by mass. The mass percentages of the positive flotation reagent raw materials are: 50% dodecyl propyl ether amine, 39.6% dodecylamine, and 10.4% acetic acid solution by mass fraction of 0.5% to 5.0% respectively; the first positive flotation reagent dosage is 190 g / t, and the second positive flotation reagent dosage is 30 g / t.

[0145] The remaining process steps and parameters are the same as those in Example 4.

[0146] The test results show that the whiteness of the phosphogypsum ore is 35% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is 90%, the SiO2 content is 3.98%, and the iron impurities (calculated as Fe2O3) are 0.38%. After flotation, the whiteness of the phosphogypsum concentrate is increased to 72.6% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is increased to 95.7%, the SiO2 content is reduced to 0.9%, the iron impurities (calculated as Fe2O3) are reduced to 0.075%, the yield of the phosphogypsum concentrate is 74.5%, and the recovery rate (calculated as CaSO4.2H2O) is 79.22%.

[0147] Comparative Example 1

[0148] The raw material composition of the reverse flotation agent in this comparative example is: 10% tributyl phosphate, 10% pineol, and 80% dodecylamine. There is less foam during the flotation process, and the removal of black impurities in the phosphogypsum is not obvious.

[0149] The test results show that the whiteness of the phosphogypsum concentrate is 39% (dried at 45°C), the iron impurity (calculated as Fe2O3) is 0.3%, the grade (calculated as CaSO4.2H2O) is 90.5%, and the yield of the phosphogypsum concentrate is 98%.

[0150] Comparative Example 2

[0151] The raw material composition of the reverse flotation agent in this comparative example is: 10% terpineol and 90% tetradecyl dimethyl tertiary amine. During the flotation process, the foam is large and there is an excessive foaming phenomenon. The foam entrains a large amount of liquid, resulting in a serious reduction in the concentrate yield.

[0152] The test results show that the whiteness of the phosphogypsum concentrate is 58% (dried at 45°C), the grade (calculated as CaSO4.2H2O) is 90.5%, and the yield of the phosphogypsum concentrate is 68%.

[0153] Comparative Example 3

[0154] The raw material composition of the reverse flotation agent in this comparative example is: 10% tributyl phosphate, 10% terpineol, and 80% tetradecyl dimethyl tertiary amine. The removal of dodecylamine causes the ability of the reverse flotation agent to remove silicon dioxide to decrease, and the concentrate purity cannot be effectively improved.

[0155] The test results show that the whiteness of the phosphogypsum concentrate is 58% (dried at 45°C), the SiO2 content is 2.6%, the grade (calculated as CaSO4.2H2O) is 90.3%, and the phosphogypsum concentrate yield is 86%.

[0156] Comparative Example 4

[0157] The raw material composition of the reverse flotation reagent in this comparative example is: oleic acid. The other process conditions are the same as those in Example 1.

[0158] The test results show that the drying whiteness of the phosphogypsum concentrate after flotation is 50% (drying temperature is 45°C), the purity of the phosphogypsum after flotation (calculated as CaSO4.2H2O) is 90.2%, and the yield of the phosphogypsum concentrate is 60%.

[0159] By comparing Examples 1 to 3 and Comparative Example 4, it can be seen that under the same flotation process and the same flotation effect, the whitening and impurity removal effect of using oleic acid as the reverse flotation agent is significantly lower than that of the present invention.

[0160] By comparing Examples 1 to 3 with Comparative Example 1, it can be seen that only a mixture of tributyl phosphate, terpineol and dodecylamine in a weight ratio of 10:10:80 is used as a reverse flotation agent, which cannot form a large amount of foam layer to float out impurities. Therefore, the whiteness of the phosphogypsum concentrate is only 39%, and the CaSO4·2H2O content is 90.5%.

[0161] By comparing Examples 1 to 3 and Comparative Example 2, it can be seen that when only a mixture of pineol and tetradecyl dimethyl tertiary amine in a weight ratio of 10:90 is used as the reverse flotation agent, the system has serious excessive foaming and entrainment, which seriously affects the selectivity of the flotation agent, so the whiteness of the phosphogypsum concentrate is only 58%, and the concentrate yield is only 68%.

[0162] By comparing Examples 1 to 3 and Comparative Example 3, it can be seen that when only a mixture of tributyl phosphate, pineneol and tetradecyl dimethyl tertiary amine in a weight ratio of 10:10:80 is used as the reverse flotation agent, the foam is large during the flotation process, there is excessive foaming, the foam entrains a large amount of liquid, resulting in a decrease in the concentrate yield, and the removal of dodecylamine causes a decrease in the ability of the reverse flotation agent to remove silica, and the concentrate purity cannot be effectively improved. Therefore, the whiteness of the phosphogypsum concentrate is only 58%, the SiO2 content is 2.6%, and the grade (calculated as CaSO4.2H2O) is 90.3%, which is significantly lower than that of the embodiments of the present invention.

[0163] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A phosphogypsum reverse flotation whitening and impurity removal agent, characterized in that: The agent is tributyl phosphate, terpineol, a fatty alkyl (R) carbon chain length of C 12 ~C 20 The carbon chain length of the fatty primary amine (R-NH2) and fatty alkyl (R) is C 12 ~C 20 A compound agent of dimethyl tertiary amine (RN(CH3)2).

2. The phosphogypsum reverse flotation whitening and impurity removal agent according to claim 1, characterized in that: The fatty primary amine (R-NH2) is one or more of dodecylamine, tetradecylamine, hexadecylamine and octadecylamine.

3. The phosphogypsum reverse flotation whitening and impurity removal agent according to claim 1, characterized in that: The dimethyl tertiary amine (RN(CH3)2) is one or more of dodecyl dimethyl tertiary amine, tetradecyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, and octadecyl dimethyl tertiary amine.

4. The phosphogypsum reverse flotation whitening and impurity removal agent according to claim 1, characterized in that: The raw material composition of the agent is calculated by mass percentage as follows: tributyl phosphate: 5% to 15%; terpineol: 5% to 15%; the carbon chain length of the fatty alkyl (R) is C 12 ~C 20 Fatty primary amine (R-NH2) in the range of 30% to 60%; fatty alkyl (R) carbon chain length is C 12 ~C 20 Range of dimethyl tertiary amine (RN(CH3)2): 20% to 40%.

5. A method for preparing a phosphogypsum reverse flotation whitening and impurity removal agent, used for preparing the phosphogypsum reverse flotation whitening and impurity removal agent according to any one of claims 1 to 4, characterized in that: include: Tributyl phosphate, pinene alcohol and fatty primary amine are added into dimethyl tertiary amine solution, and mechanically stirred to obtain a reverse flotation reagent solution system; During the process of stirring and homogenizing the reverse flotation agent solution system, a certain amount of water is added to adjust the mass fraction of the reverse flotation agent solution.

6. The preparation method according to claim 5, characterized in that: The mass fraction of the dimethyl tertiary amine solution is 30-40%, and the dimethyl tertiary amine solution is activated before use.

7. The preparation method according to claim 5, characterized in that: The mechanical stirring time is 1-2 hours, and in the reverse flotation agent solution system, the mass fraction of the reverse flotation agent is 5-7%.

8. A phosphogypsum reverse flotation whitening and impurity removal process, using the phosphogypsum reverse flotation whitening and impurity removal agent according to any one of claims 1 to 4 or the phosphogypsum reverse flotation whitening and impurity removal agent prepared according to any one of claims 5 to 7, characterized in that: The steps include: Step 1: connect two cyclone-static microbubble flotation columns in series; Step 2: transporting the phosphogypsum to be treated to a slurry mixing tank for slurry mixing to obtain phosphogypsum slurry; Step 3: The phosphogypsum slurry in the slurry mixing tank is pumped into the first cyclone-static microbubble flotation column, and a reverse flotation agent is added to perform the first reverse flotation to obtain the first slurry; the first slurry is pumped into the second cyclone-static microbubble flotation column, and the reverse flotation agent same as the first reverse flotation is added to perform the second reverse flotation to obtain the phosphogypsum concentrate; Step 4: The phosphogypsum concentrate obtained after two reverse flotation treatments is pumped into a plate and frame filter press for dehydration. After dehydration, the concentrate is dried to obtain whitened and impurity-free phosphogypsum.

9. The whitening and impurity removal process according to claim 8, characterized in that: In the step 2, the pH of the phosphogypsum slurry is 1 to 3, and the mass concentration of the slurry is 30% to 40%.

Images