Method for reducing magnesium sulfate content in sylvite flotation

Abstract

The invention discloses a method for reducing the content of magnesium sulfate in sylvite flotation. The method comprises the following steps: crushing carnallite containing magnesium sulfate, adding water to decompose the carnallite, and adding a regulator and a surfactant to form mixed slurry; roughing, primary concentration, secondary concentration and scavenging are conducted on the mixed slurry, an anion collecting agent and a foaming agent are added in the roughing stage and the scavenging stage, and flotation concentrate obtained after secondary concentration is finished is a crude potassium product. According to the method, saturated fatty acid is adopted as an anion collecting agent, alkyl sulfonate is adopted as a surfactant, metaphosphate is adopted as a regulator, and dihydric alcohol is adopted as a foaming agent, so that the selectivity of the saturated fatty acid collecting agent to sylvite is improved, meanwhile, the adsorption effect on magnesium sulfate in the sylvite flotation process is inhibited, and the potassium yield is increased; the content of magnesium sulfate in the crude potassium product in the flotation stage is reduced, and the technological process is simple and easy to operate, compact in flow and easy to realize large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of utilization of mineral resources, and particularly relates to a method for improving the potassium recovery rate and reducing the magnesium sulfate content in the crude potassium product in the flotation stage. Background Art

[0002] Carnallite ore is the most common raw material for potassium fertilizer production. Currently, it mainly comes from the evaporation of salt pans in salt lake brines. According to different types of salt lakes, the carnallite ore in salt pans is divided into two categories: one is chloride-type salt lake brine, and the main mineral components of the carnallite ore evaporated in the salt pan are carnallite and halite; the other is sulfate-type salt lake brine, and the main mineral components of the carnallite ore evaporated in the salt pan are carnallite, halite and epsomite. Regardless of which type of carnallite ore in the salt pan, in the process of processing and producing potassium fertilizer, the flotation process is a key and very important link.

[0003] The basic principle of producing potassium fertilizer from carnallite is: based on the K + , Mg 2+ / / Cl - -H2O ternary water-salt system phase diagram, through process calculation, determine the appropriate amount of water added to dissolve all the magnesium chloride into the liquid phase and crystallize potassium chloride, and the following reaction occurs:

[0004]

[0005] In the above process, all the magnesium chloride enters the liquid phase, and potassium chloride crystallizes out and exists in the system as a solid phase. For chloride-type salt pan carnallite, the presence of halite, i.e., sodium chloride, affects this reaction process, which is reflected in: sodium chloride dissolves quickly in the initial low-magnesium-chloride solution, but as the decomposition process proceeds, due to the very fast dissolution rate of magnesium chloride, the saturation of sodium chloride increases, resulting in supersaturation, and the previously dissolved sodium chloride recrystallizes out again and exists in the system in the form of fine-grained sodium chloride. This newly formed sodium chloride affects the decomposition potassium recovery rate and subsequent potassium salt flotation, and is the key restricting the production of potassium fertilizer using chloride-type salt pan carnallite ore. Similarly, for sulfate-type salt pan carnallite, in addition to halite, the presence of epsomite, i.e., magnesium sulfate, also affects this reaction process, that is, the recrystallization of magnesium sulfate occurs, and the newly formed magnesium sulfate affects the decomposition potassium recovery rate and subsequent potassium salt flotation, and is the key restricting the production of potassium fertilizer using sulfate-type salt pan carnallite ore.

[0006] CN111282718A discloses a flotation process for potassium chloride in a magnesium sulfate subtype salt lake, which effectively reduces the sodium chloride content in the potassium chloride concentrate and improves the flotation environment during the production of potassium chloride by pre-flotation of kainite and strengthening the potassium chloride flotation process. CN103073029A discloses a method for processing and producing potassium chloride from potassium-bearing salt lake brine of magnesium sulfate subtype or sulfate-chloride transition type. Through brine modification, sylvite and carnallite are obtained, and potassium chloride products are obtained after flotation.

[0007] However, the technical routes adopted in the above patents and literatures are all for the flotation process of potassium chloride in carnallite ore of sulfate type salt pans. Through the strengthening of the flotation process, the sodium chloride content is effectively reduced, the flotation environment system is improved, and the potassium recovery rate is increased. The main focus is on the effective separation of potassium salts and sodium salts. However, the influence of magnesium sulfate on the flotation process during the potassium salt flotation process of carnallite ore containing epsomite has not been reported. Summary of the Invention

[0008] The main object of the present invention is to provide a method for strengthening the potassium salt flotation process and reducing the magnesium sulfate content in potassium chloride products for carnallite ore containing magnesium sulfate, so as to overcome the deficiencies in the prior art.

[0009] To achieve the foregoing invention object, the technical solutions adopted by the present invention include:

[0010] An embodiment of the present invention provides a method for reducing the magnesium sulfate content in potassium salt flotation, which includes:

[0011] Crush the carnallite ore containing magnesium sulfate, add water to decompose the carnallite ore, and add a regulator and a surfactant to form a mixed slurry. The regulator includes metaphosphate, and the surfactant includes alkyl sulfonate;

[0012] Conduct rough selection, primary cleaning, secondary cleaning and scavenging on the mixed slurry, and add an anionic collector and a foaming agent during the rough selection and scavenging stages. The flotation concentrate obtained at the end of the secondary cleaning is the crude potassium product, and the magnesium sulfate content in the crude potassium product is reduced to less than 11.5%. The anionic collector includes saturated fatty acid, and the foaming agent includes diol.

[0013] In some embodiments, the chemical formula of the metaphosphate is (NaPO3) n , where n is 3-6.

[0014] In some embodiments, the surfactant includes alkyl sulfonate, and the length of the alkyl carbon chain is 12-16.

[0015] In some embodiments, the anionic collector includes saturated fatty acid, and the length of the alkyl carbon chain is 6-12.

[0016] In some embodiments, the foaming agent includes dihydric alcohols with 2 to 5 carbon atoms.

[0017] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0018] The method for reducing the content of magnesium sulfate in potassium salt flotation provided by the present invention uses saturated fatty acids as anionic collectors, alkyl sulfonates as surfactants, metaphosphates as regulators, and dihydric alcohols as foaming agents, improving the selectivity of the saturated fatty acid collector for potassium salts, while inhibiting the adsorption of magnesium sulfate during the potassium salt flotation process, increasing the potassium recovery rate, reducing the content of magnesium sulfate in the crude potassium product in the flotation stage, and having a process flow that is simple and easy to operate, has a compact process, and is easy to achieve large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a process flow diagram for reducing the content of magnesium sulfate in potassium salt flotation in a typical embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In view of the deficiencies of the prior art, the inventors of this case have, through long-term research and a large number of practices, been able to propose the technical solution of the present invention, which mainly provides a method for reducing the content of epsomite (MgSO4·7H2O) in the process of producing potassium chloride (KCl) from carnallite (KCl·MgCl2·6H2O) ore, specifically related to a method using saturated fatty acids as collectors, alkyl sulfonates as surfactants, metaphosphates as regulators, and dihydric alcohols as foaming agents, improving the selectivity of the saturated fatty acid collector for potassium salts, while inhibiting the adsorption of magnesium sulfate during the potassium salt flotation process, increasing the potassium recovery rate, and reducing the content of magnesium sulfate in the crude potassium product in the flotation stage.

[0022] The following will clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] Specifically, as an aspect of the technical solution of the present invention, a method for reducing the content of magnesium sulfate in potassium salt flotation involves:

[0024] Crush the carnallite ore containing magnesium sulfate, add water to decompose the carnallite ore, and add a regulator and a surfactant to form a mixed slurry;

[0025] Carry out rough selection, first-stage concentration, second-stage concentration and scavenging on the mixed slurry, and add an anionic collector and a foaming agent in the rough selection and scavenging stages. The flotation concentrate obtained at the end of the second-stage concentration is the crude potassium product, and the content of magnesium sulfate in the crude potassium product is reduced to less than 11.5%.

[0026] In some embodiments, the method includes: crushing the carnallite ore containing magnesium sulfate to less than 2 mm.

[0027] In some embodiments, the crushing method includes using a counterattack crusher for crushing.

[0028] In some embodiments, the content of carnallite in the carnallite ore containing magnesium sulfate is 45.37 - 63.13 wt%, the content of magnesium sulfate is 15.39 - 22.81 wt%, the content of sodium chloride is 13.21 - 21.57 wt%, the content of bischofite is 4.62 - 6.31 wt%, and other water-insoluble substances are 1.96 - 5.63%.

[0029] In some embodiments, the method includes: the mass ratio of the added water to the carnallite ore containing magnesium sulfate is 1:2.5 - 3.4 to form a slurry.

[0030] In some embodiments, the method further includes: adding saturated mother liquor to the slurry for pulp adjustment to make the solid-liquid ratio 1:2 - 3, and carrying out a conversion reaction for 30 - 90 min. Adding water is for the conversion reaction of decomposing the carnallite ore containing magnesium sulfate into potassium chloride.

[0031] In some embodiments, the content of sodium chloride in the saturated mother liquor is 1.36 - 2.85 wt%, the content of magnesium sulfate is 3.13 - 5.78 wt%, the content of magnesium chloride is 21.54 - 23.47 wt%, and the content of potassium chloride is 2.54 - 3.74 wt%.

[0032] In some embodiments, the chemical formula of the metaphosphate is (NaPO3) n , where n is 3 - 6.

[0033] In some more preferred embodiments, the metaphosphate may include at least any one of sodium hexametaphosphate, sodium trimetaphosphate, etc., but is not limited thereto.

[0034] In some more preferred embodiments, the dosage of the regulator is 40 - 90 grams per ton.

[0035] In some embodiments, the surfactant includes alkyl sulfonate, and the length of the alkyl carbon chain is 12 to 16.

[0036] In some more preferred embodiments, the dosage of the surfactant is 40 to 200 grams per ton.

[0037] In some embodiments, the method includes: adding a regulator to the slurry and stirring for 5 to 10 minutes; then adding the surfactant and stirring for 5 to 10 minutes.

[0038] Furthermore, the equipment used for stirring is a paddle stirrer.

[0039] In some embodiments, the anionic collector includes saturated fatty acid, and the length of the alkyl carbon chain is 6 to 12.

[0040] In some embodiments, the foaming agent includes diol, and the carbon number is 2 to 5.

[0041] In some embodiments, the method specifically includes:

[0042] Adding an anionic collector and a foaming agent to the mixed slurry, and then performing rough selection to obtain a potassium-containing product of rough selection and tailings of rough selection;

[0043] Performing primary cleaning on the potassium-containing product of rough selection to obtain a potassium-containing product of primary cleaning and tailings of primary cleaning;

[0044] Performing secondary cleaning on the potassium-containing product of primary cleaning to obtain a potassium-containing product of secondary cleaning and tailings of secondary cleaning.

[0045] In some more preferred embodiments, the method further includes: adding an anionic collector to the tailings of rough selection, and then performing scavenging to obtain a potassium-containing product of scavenging and tailings of scavenging.

[0046] In some more preferred embodiments, the method further includes: returning the tailings of primary cleaning and the potassium-containing product of scavenging to the rough selection stage.

[0047] In some more preferred embodiments, the method further includes: returning the tailings of secondary cleaning to the primary cleaning stage.

[0048] In some more preferred embodiments, the concentration of rough selection (the concentration of the slurry in the rough selection process section) is 25 wt% to 35 wt%, the concentration of scavenging is 20 wt% to 25 wt%, the concentration of primary cleaning is 15 wt% to 25 wt%, and the concentration of secondary cleaning is 15 wt% to 25 wt%.

[0049] In some more preferred embodiments, the method includes: in the rough selection stage, the dosage of the anionic collector is 200-500 g / t, the dosage of the foaming agent is 1-5 g / t, and the flotation time is 4-8 min.

[0050] In some more preferred embodiments, in the scavenging stage, the dosage of the anionic collector is 50-250 g / t, and the flotation time is 3-6 min.

[0051] Furthermore, the flotation time of the first cleaning is 2-6 min.

[0052] Furthermore, the flotation time of the second cleaning is 2-4 min.

[0053] Among them, in some more specific embodiments, as Figure 1 shown, a method for strengthening the potassium salt flotation process and reducing magnesium sulfate in the crude potassium product in the flotation stage for the magnesium sulfate-containing carnallite ore specifically includes the following steps:

[0054] (1) Crush the magnesium sulfate-containing carnallite ore to -20 mesh (-2 mm), add a certain amount of water to decompose carnallite, and at the same time add a regulator, and the dosage of the regulator is 40-90 g / t;

[0055] (2) Add a surfactant to the slurry and place it in a stirrer, and the addition amount of the surfactant is 40-200 g / t;

[0056] (3) The flotation process adopts one rough selection, two cleanings (cleaning I, cleaning II), and one scavenging. The middlings of cleaning I and the concentrate of scavenging are returned to the rough selection, and the middlings of cleaning II are returned to cleaning I, such a closed-circuit process flow. The rough selection concentration is 25 wt% - 35 wt%, the scavenging concentration is 20 wt% - 25 wt%, the cleaning concentration is 15 wt% - 25 wt%. The dosage of the anionic collector in the rough selection stage is 200-500 g / t, the dosage of the foaming agent is 1-5 g / t, the flotation time is 4-8 minutes, the dosage of the anionic collector in the scavenging stage is 50-250 g / t, the flotation time is 3-6 minutes, no collector is added in the two cleaning stages, the flotation time of cleaning I is 2-6 minutes, the flotation time of cleaning II is 2-4 minutes, and the crude potassium product is obtained through the flotation closed cycle.

[0057] To sum up, the method of the present invention uses saturated fatty acids as anionic collectors, alkyl sulfonates as surfactants, metaphosphates as regulators, and dihydric alcohols as foaming agents, improves the selectivity of the saturated fatty acid collector for potassium salts, and at the same time inhibits the adsorption of magnesium sulfate during the potassium salt flotation process, improves the potassium recovery rate, reduces the content of magnesium sulfate in the crude potassium product in the flotation stage, and has a process flow that is simple and easy to operate, has a compact process, and is easy to realize large-scale production.

[0058] The technical solution of the present invention will be further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. These embodiments are implemented on the premise of the technical solution of the invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0059] In the following embodiments, the experimental materials used can be obtained from conventional biochemical reagent companies without special instructions.

[0060] Example 1

[0061] The method for reducing the content of magnesium sulfate in the potassium salt flotation in this example includes the following steps:

[0062] (1) Crush the carnallite ore containing epsomite (carnallite content 53.89 wt%, epsomite content 19.53%, sodium chloride content 17.89 wt%, bischofite content 6.25%) to -2 mm, add water to decompose the carnallite ore, the water addition amount: ore amount = 1:3.28, adjust the pulp with saturated mother liquor to make the solid-liquid ratio 1:2, and carry out a conversion reaction for 40 minutes;

[0063] (2) The composition of the saturated mother liquor (NaCl content is 1.64 wt%, MgSO4 content is 5.10 wt%, MgCl2 content is 21.62 wt%, KCl content is 3.62 wt%);

[0064] (3) Add 45 grams / ton of the regulator sodium hexametaphosphate and stir for 10 minutes;

[0065] (4) Add 100 grams / ton of the surfactant sodium hexadecyl sulfonate and stir for 5 minutes;

[0066] (5) The flotation process adopts one roughing, two cleanings, and one scavenging. The middlings of the first cleaning and the concentrate of the scavenging are returned to the roughing, and the middlings of the second cleaning are returned to the first cleaning, such a closed-circuit process flow;

[0067] (6) The roughing concentration is 25.46 wt%, and the scavenging concentration is 21.23 wt%; 260 grams / ton of the anionic collector n-decanoic acid and 2.5 grams / ton of the glycol foaming agent are added in the roughing, the flotation time is 6 minutes, 80 grams / ton of the anionic collector n-decanoic acid is added in the scavenging, the flotation time is 5 minutes, no collector is added in the two cleanings, the concentration of the first cleaning is 18.56 wt%, the concentration of the second cleaning is 17.25 wt%, and the flotation time of the two cleanings is 4 minutes; the flotation concentrate is obtained, and the flotation concentrate is the crude potassium product, with a KCl content of 58.13%, an MgSO4 content of 7.61%, an MgCl2 content of 3.11%, and an NaCl content of 9.23%. The potassium flotation recovery rate is 86.52%.

[0068] Example 2

[0069] The method for reducing the content of magnesium sulfate in the potassium salt flotation of this embodiment includes the following steps:

[0070] (1) Crush the carnallite ore containing epsomite (carnallite content 53.89 wt%, epsomite content 19.53%, sodium chloride content 17.89 wt%, bischofite content 6.25%) to -2 mm, add water to decompose the carnallite ore, the water addition amount: ore amount = 1:3.28, adjust the pulp with saturated mother liquor to make the solid-liquid ratio 1:2.5, and carry out the conversion reaction for 40 minutes;

[0071] (2) The composition of the saturated mother liquor (NaCl content is 1.64 wt%, MgSO4 content is 5.10 wt%, MgCl2 content is 21.62 wt%, KCl content is 3.62 wt%);

[0072] (3) Add 60 grams / ton of the regulator sodium tripolyphosphate and stir for 10 minutes;

[0073] (4) Add 50 grams / ton of the surfactant sodium dodecyl sulfonate and stir for 5 minutes;

[0074] (5) The flotation process adopts one rough selection, two fine selections, and one scavenging. The middlings of the first fine selection and the concentrate of the scavenging are returned to the rough selection, and the middlings of the second fine selection are returned to the first fine selection, such a closed-circuit process flow;

[0075] (6) The rough selection concentration is 27.45 wt%, and the scavenging concentration is 22.18 wt%; 300 grams / ton of the anionic collector lauric acid and 2 grams / ton of the 1,2-propanediol foaming agent are added in the rough selection, the flotation time is 6 minutes, 60 grams / ton of the anionic collector lauric acid is added in the scavenging, the flotation time is 5 minutes, no collector is added in the two fine selections, the concentration of the first fine selection is 16.39 wt%, the concentration of the second fine selection is 22.56 wt%, and the flotation time of the two fine selections is 4 minutes; the flotation concentrate is obtained, and the flotation concentrate is the crude potassium product, with the KCl content being 58.70%, the MgSO4 content being 7.54 wt%, the MgCl2 content being 3.67 wt%, and the NaCl content being 6.08 wt%. The potassium flotation recovery rate is 85.23%.

[0076] Example 3

[0077] The method for reducing the content of magnesium sulfate in the potassium salt flotation of this embodiment includes the following steps:

[0078] (1) Crush the carnallite ore containing epsomite (carnallite content 53.89 wt%, epsomite content 19.53%, sodium chloride content 17.89 wt%, bischofite content 6.25%) to -2 mm, add water to decompose the carnallite ore, the water addition amount: ore amount = 1:3.28, adjust the pulp with saturated mother liquor to make the solid-liquid ratio 1:2, and carry out the conversion reaction for 40 minutes;

[0079] (2) Composition of the saturated mother liquor (NaCl content is 1.64 wt%, MgSO4 content is 5.10 wt%, MgCl2 content is 21.62 wt%, KCl content is 3.62 wt%);

[0080] (3) Add 70 g / ton of the regulator sodium hexametaphosphate and stir for 10 minutes;

[0081] (4) Add 60 g / ton of the surfactant sodium dodecyl sulfonate and stir for 5 minutes;

[0082] (5) The flotation process adopts one roughing, two cleanings, and one scavenging. The middlings of the first cleaning and the concentrate of the scavenging are returned to the roughing, and the middlings of the second cleaning are returned to the first cleaning, such a closed-circuit process flow;

[0083] (6) The roughing concentration is 28.45 wt%, and the scavenging concentration is 23.65 wt%; 350 g / ton of the anionic collector myristic acid and 3 g / ton of the foaming agent 1,5-pentanediol are added in the roughing, the flotation time is 6 minutes, 60 g / ton of the anionic collector myristic acid is added in the scavenging, the flotation time is 5 minutes, no collector is added in the two cleanings, the concentration of the first cleaning is 17.33 wt%, the concentration of the second cleaning is 21.92 wt%, and the flotation time of the two cleanings is 4 minutes; the flotation concentrate is obtained, and the flotation concentrate is the crude potassium product, with KCl content of 51.88%, MgSO4 content of 11.05 wt%, MgCl2 content of 3.68 wt%, and NaCl content of 5.76 wt%. The potassium flotation recovery rate is 87.68%.

[0084] Example 4

[0085] The method for reducing the magnesium sulfate content in the potassium salt flotation of this example includes the following steps:

[0086] (1) Crush the carnallite ore containing epsomite (carnallite content 53.89 wt%, epsomite content 19.53%, sodium chloride content 17.89%, bischofite content 6.25%) to -2 mm, add water to decompose the carnallite ore, the water addition amount: ore amount = 1:2.64, adjust the pulp with the saturated mother liquor to make the solid-liquid ratio 1:2.8, and carry out the conversion reaction for 70 minutes;

[0087] (2) Composition of the saturated mother liquor (NaCl content is 2.31 wt%, MgSO4 content is 4.95 wt%, MgCl2 content is 22.42 wt%, KCl content is 2.98 wt%);

[0088] (3) Add 80 g / ton of the regulator sodium hexametaphosphate and stir for 8 minutes;

[0089] (4) Add 160 g / t of sodium dodecyl sulfonate, a surfactant, and stir for 6 minutes;

[0090] (5) The flotation process adopts one rough selection, two fine selections, and one scavenging. The middlings of the first fine selection and the concentrate of the scavenging are returned to the rough selection, and the middlings of the second fine selection are returned to the first fine selection, forming a closed-circuit process flow like this;

[0091] (6) The rough selection concentration is 25.03 wt%, and the scavenging concentration is 20.85 wt%. In the rough selection, add 350 g / t of myristic acid, an anionic collector, and 3 g / t of 1,5-pentanediol foaming agent, and the flotation time is 6 minutes. In the scavenging, add 60 g / t of myristic acid, an anionic collector, and the flotation time is 5 minutes. No collector is added in the two fine selections. The concentration of the first fine selection is 24.65 wt%, and the concentration of the second fine selection is 18.37 wt%. The flotation time for both fine selections is 4 minutes. Obtain the flotation concentrate. The flotation concentrate is the crude potassium product, with a KCl content of 54.75%, an MgSO4 content of 8.35 wt%, an MgCl2 content of 4.31 wt%, and an NaCl content of 4.97 wt%. The potassium flotation recovery rate is 86.45%.

[0092] Comparative Example 1

[0093] The method for reducing the content of magnesium sulfate in the potassium salt flotation of this comparative example includes the following steps:

[0094] (1) Crush the carnallite ore containing epsomite (carnallite content 53.89 wt%, epsomite content 19.53%, sodium chloride content 17.89%, bischofite content 6.25%) to -2 mm, add water to decompose the carnallite ore, the water addition amount: ore amount = 0.304, adjust the pulp with saturated mother liquor to make the solid-liquid ratio 1:2, and carry out the conversion reaction for 40 minutes;

[0095] (2) Composition of the saturated mother liquor (sodium chloride content 1.64 wt%, magnesium sulfate content 5.10 wt%, magnesium chloride content 21.62 wt%, potassium chloride content 3.62 wt%);

[0096] (3) The flotation process adopts one rough selection, two fine selections, and one scavenging. The middlings of the first fine selection and the concentrate of the scavenging are returned to the rough selection, and the middlings of the second fine selection are returned to the first fine selection, forming a closed-circuit process flow like this.

[0097] (4) The rough selection concentration is 27.45 wt%, and the scavenging concentration is 20.63 wt%; 360 g / t of octadecylamine hydrochloride and 5 g / t of turpentine foaming agent are added during rough selection, the flotation time is 6 minutes, 80 g / t of octadecylamine hydrochloride is added during scavenging, and the flotation time is 5 minutes. No collector is added during the two-stage cleaning. The concentration of the first-stage cleaning is 23.25 wt%, and the concentration of the second-stage cleaning is 19.73 wt%. The flotation time for both stages of cleaning is 4 minutes; Flotation concentrate is obtained. The flotation concentrate is the crude potassium product, with a KCl content of 50.43%, an MgSO4 content of 15.62 wt%, an MgCl2 content of 2.75 wt%, and an NaCl content of 6.79 wt%. The potassium flotation recovery rate is 82.39%.

[0098] Comparative Example 2

[0099] Compared with Example 1, the difference is that the regulator sodium hexametaphosphate was not added. The final flotation concentrate is the crude potassium product, with a KCl content of 54.05%, an MgSO4 content of 8.52 wt%, an MgCl2 content of 3.08 wt%, and an NaCl content of 9.78 wt%. The potassium flotation recovery rate is 83.25%.

[0100] Comparative Example 3

[0101] Compared with Example 1, the difference is that the surfactant sodium hexadecyl sulfonate was not added. The final flotation concentrate is the crude potassium product, with a KCl content of 51.65%, an MgSO4 content of 13.23 wt%, an MgCl2 content of 2.35 wt%, and an NaCl content of 7.21 wt%. The potassium flotation recovery rate is 83.56%.

[0102] Comparative Example 4

[0103] Compared with Example 1, the difference is that the foaming agent ethylene glycol was not added during rough selection. The final flotation concentrate is the crude potassium product, with a KCl content of 50.56%, an MgSO4 content of 12.33 wt%, an MgCl2 content of 3.25 wt%, and an NaCl content of 6.02 wt%. The potassium flotation recovery rate is 78.62%.

[0104] Comparative Example 5

[0105] Compared with Example 1, the difference is that the anionic collector n-decanoic acid was not added during scavenging. The final flotation concentrate is the crude potassium product, with a KCl content of 55.67%, an MgSO4 content of 8.03 wt%, an MgCl2 content of 3.08 wt%, and an NaCl content of 8.54 wt%. The potassium flotation recovery rate is 81.25%.

[0106] In addition, with reference to the foregoing embodiments, the inventors of this case also conducted tests using other raw materials, process operations, and process conditions described in this specification, and all obtained relatively ideal results.

[0107] It should be understood that the technical solutions of the present invention are not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solutions of the present invention without departing from the spirit of the present invention and the scope protected by the claims falls within the protection scope of the present invention.

Claims

1. A method for reducing the content of magnesium sulfate in potassium salt flotation, characterized in that: include: Crushing the magnesium sulfate-containing carnallite ore, adding water to decompose the carnallite ore, and adding an adjusting agent and a surfactant to form a mixed slurry, wherein the adjusting agent includes metaphosphate and the surfactant includes alkyl sulfonate; The mixed slurry is subjected to roughing, primary cleaning, secondary cleaning and scavenging, and an anion collector and a frother are added in the roughing and scavenging stages. The flotation concentrate obtained after the secondary cleaning is a crude potassium product, and the content of magnesium sulfate in the crude potassium product is reduced by less than 11.5%. The anion collector includes a saturated fatty acid, and the frother includes a diol.

2. The method according to claim 1, characterized in that: include: Crushing the magnesium sulfate-containing carnallite ore to a size less than 2 mm; and / or, the crushing method includes crushing with an impact crusher; And / or, the content of carnallite in the magnesium sulfate-containing carnallite ore is 45.37-63.13wt%, the content of magnesium sulfate is 15.39-22.81wt%, the content of sodium chloride is 13.21-21.57wt%, the content of bischofite is 4.62-6.31wt%, and other water-insoluble substances are 1.96-5.63%.

3. The method according to claim 1, characterized in that include: The mass ratio of water added to magnesium sulfate-containing carnallite ore is 1:2.5-3.4 to form a slurry; And / or, the method further comprises: adding saturated mother liquor to the slurry to adjust the slurry so that the solid-liquid ratio is 1:2-3, and the conversion reaction takes 30-90 minutes; Preferably, the content of sodium chloride in the saturated mother liquor is 1.36-2.85wt%, the content of magnesium sulfate is 3.13-5.78wt%, the content of magnesium chloride is 21.54-23.47wt%, and the content of potassium chloride is 2.54-3.74wt%.

4. The method according to claim 1, characterized in that: The chemical formula of the metaphosphate is (NaPO3) n , n is 3 to 6; preferably, the metaphosphate includes at least one of sodium hexametaphosphate and sodium trimetaphosphate; And / or, the dosage of the adjusting agent is 40 to 90 g / ton.

5. The method according to claim 1, characterized in that: The surfactant comprises an alkyl sulfonate, and the length of the alkyl carbon chain is 12 to 16; and / or, the amount of the surfactant is 40 to 200 g / ton; And / or, the method comprises: adding a conditioning agent to the slurry and stirring for 5 to 10 minutes; then adding a surfactant and stirring for 5 to 10 minutes; Preferably, the stirring device is a paddle stirrer.

6. The method according to claim 1, characterized in that: The anion collector comprises a saturated fatty acid, and the length of the alkyl carbon chain is 6 to 12; and / or the foaming agent comprises a diol, and the carbon number is 2 to 5.

7. The method according to claim 1, characterized in that include: An anion collector and a frother are added to the mixed slurry, followed by roughing to obtain a rough potassium-containing product and rough tailings; Performing primary concentrating on the rough potassium-containing product to obtain a primary concentrating potassium-containing product and a primary concentrating tailings; The primary concentrated potassium-containing product is subjected to secondary concentration to obtain a secondary concentrated potassium-containing product and a secondary concentrated tailings.

8. The method according to claim 7, characterized in that Also includes: Adding an anion collector to the roughing tailings, followed by scavenging to obtain scavenged potassium-containing products and scavenged tailings; Preferably, the method further comprises: returning the primary concentrated tailings and scavenged potassium-containing products to the roughing stage; Preferably, the method further comprises: returning the secondary concentration tailings to the primary concentration stage.

9. The method according to claim 8, characterized in that: The concentration of the roughing selection is 25wt% to 35wt%, the concentration of the scavenging selection is 20wt% to 25wt%, the concentration of the primary cleaning selection is 15wt% to 25wt%, and the concentration of the secondary cleaning selection is 15wt% to 25wt%.

10. The method according to claim 8, characterized in that include: In the roughing stage, the dosage of anionic collector is 200-500 g / ton, the dosage of frother is 1-5 g / ton, and the flotation time is 4-8 min. and / or, in the scavenging stage, the dosage of the anion collector is 50 to 250 g / ton, and the flotation time is 3 to 6 min; And / or, the flotation time of the primary concentration is 2 to 6 minutes; And / or, the flotation time of the secondary concentration is 2 to 4 minutes.

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