Method for purification and whitening of barite

Abstract

The application discloses a method for purifying and whitening barite, and belongs to the technical field of mineral processing technology. The application first provides a complexing agent as shown in formula a, which is prepared by amidation reaction of taurine and 4-(chloroformyl)benzoic acid methyl ester, and the complexing ability of the complexing agent to metal ions is better than that of EDTA-2Na which is better in traditional complexing agents. The complexing agent can be used for purifying and whitening barite, and when applied, the mass ratio of the complexing agent to barite is (0.1-0.5):10. The method for purifying and whitening barite provided by the application can not only obtain a barite product with a whiteness of more than 92% through process steps such as acid pickling, complexing impurity removal, reverse flotation silicon removal and calcination treatment, but also effectively overcome the defects of poor degradability and insufficient environmental friendliness of the existing complexing agent.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, and more specifically, relates to a method for purifying and whitening barite. Background Technology

[0002] Barite's main component is barium sulfate (BaSO4), and it has wide and important applications in fields such as oil drilling mud weighting agents, chemical raw materials (for the production of pigments such as barium carbonate, barium sulfate, and zinc barium white), building materials, and pharmaceuticals.

[0003] my country has abundant barite resources, but most natural barite ores have high impurity content, especially rich in coloring metal impurities such as iron, manganese, and nickel, as well as gangue impurities such as quartz, calcite, clay, and carbonaceous matter. This results in generally low whiteness of the raw ore, with most low-grade raw ores having a whiteness of only 30% to 60%, which is difficult to meet the requirements of paint, pigment, and high-end chemical industries, which typically require a whiteness of greater than 90%.

[0004] Currently, barite purification technologies mainly fall into four categories: manual selection, gravity separation, magnetic separation, and chemical purification. Among these, physical methods such as manual selection, gravity separation, and magnetic separation are primarily suitable for raw ores with significant differences between impurities and barite. For barite ores with finely embedded impurities, especially those containing coloring impurities such as carbon, iron, manganese, and nickel, the purification effect is limited. In contrast, chemical purification achieves selective removal of impurities through chemical reactions, resulting in a more significant purification effect on the aforementioned difficult-to-process barite ores. It has become the mainstream technology for preparing high-purity, high-whiteness barite. The acid leaching-complexation combined process, in particular, is widely used for the deep purification of barite due to its effective removal of metallic coloring impurities.

[0005] Existing chemical purification and whitening technologies mainly include the hydrofluoric acid method, the sulfuric acid complexation method, and the sulfuric acid calcination method. The hydrofluoric acid method only achieves a whiteness of 88% for barite, and hydrofluoric acid is highly corrosive, posing safety hazards and environmental risks. The sulfuric acid complexation method results in even lower whiteness, only 84.72%, which is insufficient to meet high-end requirements. While the sulfuric acid calcination method can increase whiteness to 93.5%, it generates difficult-to-remove calcium sulfate precipitate, leading to residual calcium impurities that affect product purity. Furthermore, this process is energy-intensive and costly.

[0006] Furthermore, as the core reagent in the acid leaching-complexing process, the complexing ability and environmental compatibility of the complexing agent directly determine the purification effect of barite and the environmental friendliness of the process. Commonly used complexing agents in existing technologies include disodium ethylenediaminetetraacetate (EDTA-2Na), oxalic acid, and ascorbic acid. Aminocarboxylic acid chelating agents, represented by EDTA-2Na, are particularly effective against metal ions (such as Fe). 3 + Mn 2+EDTA-2Na (e.g., EDTA-2Na) possesses strong complexing capabilities, effectively stabilizing metal ions dissolved after acid leaching in solution and preventing their re-adsorption or deposition on the barite surface. This plays a crucial role in improving the impurity removal efficiency and whiteness of the concentrate. However, numerous studies have shown that EDTA-2Na exhibits poor biodegradability in the natural environment and strong persistence in wastewater treatment systems and receiving water bodies. It readily forms stable complexes with heavy metals in soil or sediments, altering the migration, transformation, and bioavailability of heavy metals, thus posing potential ecological risks and inhibiting microorganisms in wastewater treatment. Research in the remediation of heavy metal-contaminated soil and water also indicates that while EDTA-2Na can significantly improve the migration of heavy metals, its poor biodegradability and long residual time make it one of the complexing agents with significant environmental safety controversies. Therefore, while existing complexing purification systems based on EDTA-2Na achieve high impurity removal efficiency, they also bring problems such as difficult wastewater treatment and significant environmental risks. However, complexing agents such as oxalic acid and ascorbic acid have insufficient complexing ability for metal ions, making it difficult to obtain barite products with high whiteness.

[0007] In summary, existing barite purification and whitening technologies present significant contradictions in terms of impurity removal efficiency, product whiteness, and environmental friendliness. While processes relying on HF or traditional inorganic acids and complexing agents such as EDTA-2Na can improve whiteness and purity to some extent, they suffer from prominent problems such as high toxicity, poor biodegradability, difficult wastewater treatment, and potential environmental risks. Therefore, it is necessary to develop a barite purification and whitening method that possesses strong metal ion complexing ability, achieves deep impurity removal and high whitening, while also exhibiting good biodegradability and environmental friendliness. Summary of the Invention

[0008] 1. The problem to be solved To address the conflict between impurity removal effectiveness, product whiteness, and environmental friendliness in existing barite purification and whitening technologies, this invention provides a complexing agent and a method for purifying and whitening barite using this complexing agent. This method can obtain barite products with high whiteness and purity while ensuring the environmental friendliness of the purification and whitening process.

[0009] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a complexing agent, the structural formula of which is shown in formula a: .

[0010] The second aspect of the present invention provides the application of a complexing agent provided by any of the technical solutions of the first aspect of the present invention in the purification and whitening of barite, wherein the mass ratio of the complexing agent to the barite is (0.1~0.5):10.

[0011] A third aspect of the present invention provides a method for purifying and whitening barite, comprising the following steps: (1) Provide barite after crushing and grinding, and wash the barite with deionized water; (2) The wet product obtained in step (1) is immersed in an inorganic acid solution and stirred at 30~80℃ for 3~6 hours. After the reaction, the solid and liquid are separated and washed with water to obtain the acid-washed and purified barite wet material. (3) Provide a slurry containing the barite wet material, deionized water and complexing agent, adjust the pH value of the slurry to 5-6, stir and complex at 50-80°C for 4-10 hours, and then filter and wash. (4) Provide a mixed slurry containing the product obtained in step (3), a collector, an inhibitor and deionized water, and after ultrasonic dispersion, react for 6 to 12 hours at 40 to 80°C and 200 to 500 rpm. After the reaction is completed, let it stand, separate and discard the upper suspension, and dry the lower solid. (5) The dried solid is calcined at high temperature to obtain the purified and whitened barite product; The structure of the complexing agent mentioned in step (3) is shown in formula a: (Abbreviated as MMT-TA).

[0012] The compound shown in Formula a was prepared from taurine and methyl 4-carboxybenzoate. The resulting MMT-TA has an amide structure and exhibits good biodegradability from raw materials to product. Furthermore, the results show that using it as a complexing agent for the purification and whitening of barite yields barite products with a whiteness exceeding 92%, demonstrating good complexing ability.

[0013] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (1), the particle size of the barite after crushing and grinding is less than or equal to 150 μm.

[0014] The smaller particle size of barite after crushing and grinding helps to increase the surface area in contact with inorganic acids, which can fully dissolve impurities in barite.

[0015] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (2), the inorganic acid includes one or two of hydrochloric acid and nitric acid.

[0016] Inorganic acids can dissolve metals or metal oxides in barite for removal.

[0017] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (2), the concentration of the inorganic acid solution is 1~4 mol / L; The amount of inorganic acid solution used is controlled so that the liquid-solid ratio of inorganic acid solution to barite is 2~5 mL / g.

[0018] It should be noted that the mass of barite in the liquid-solid ratio of the inorganic acid solution to barite refers to the dry weight of the barite after crushing and grinding in step (1), and the mass of barite in the feeding ratio involved in this application all have this meaning.

[0019] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (3), the mass ratio of the complexing agent to barite in the slurry to be complexed is (0.1~0.5):10; The barite contains 75-90% barium sulfate.

[0020] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (3), the concentration of the complexing agent in the slurry to be complexed is 0.005~0.02 g / mL.

[0021] Complexing agents can complex and adsorb metal ions on barite, further improving the purification of barite and achieving the purpose of impurity removal and purification. They have a significant impact on the whiteness of the final product, barite.

[0022] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (3), the pH value of the slurry system to be complexed is adjusted by adding one or more of NaOH, Na2CO3, and NaHCO3.

[0023] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (4), the collector includes one or more of sodium stearate, sodium oleate, sodium hexadecyl sulfate, and sodium hexametaphosphate; The inhibitors include one or more of tannic acid, glucose, and cyclodextrin.

[0024] It should be noted that the inhibitors selected in this invention (such as tannic acid, glucose, and cyclodextrin) contain a large number of hydroxyl groups in their molecular structure. During reverse flotation for silica removal, these hydroxyl groups preferentially adsorb onto the surface of silicate impurities such as quartz through hydrogen bonding or electrostatic interactions, making the quartz surface more readily interact with collectors such as sodium stearate, thereby enhancing the hydrophobicity of the quartz and forming a stable suspension. In contrast, barite (BaSO4) is not easily adsorbed by collectors in this system, and its higher density causes it to settle rapidly. This selective adsorption and sedimentation behavior allows for the effective separation of impurities such as quartz from barite. In short, inhibitors such as tannic acid, glucose, and cyclodextrin more readily adsorb impurities such as quartz and calcite in barite, and can synergistically form micelles with collectors, enhancing the buoyancy of impurities such as quartz and selectively inhibiting the suspension of BaSO4, thus separating barite from impurities.

[0025] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (4), the mass ratio of barite to inhibitor in the slurry is 100:(0.8~1.2). The mass ratio of barite to collector in the slurry is 100:(7~15).

[0026] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (4), the mass-to-volume ratio of barite to deionized water in the slurry is 1g:(5~10)mL. That is, 1g of barite corresponds to 5~10mL of deionized water.

[0027] As a preferred embodiment of any technical solution in the third aspect of the present invention, silicon removal is carried out once or multiple times according to the conditions of step (4), preferably 3 to 5 times.

[0028] As a preferred embodiment of any technical solution in the third aspect of the present invention, in step (5), the conditions for high-temperature calcination are to heat the temperature to 700-1100°C at a heating rate of 2-4°C / min and hold the temperature for calcination for 2-4 hours.

[0029] Further preferred, in step (5), the high-temperature calcination temperature is 800~900℃.

[0030] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The complexing agent provided by the present invention and its application in the purification and whitening of barite, using the compound shown in formula a as the complexing agent, has a better complexing ability for metal ions than EDTA-2Na, which performs better among traditional complexing agents. The compound shown in formula a is obtained by amidation reaction of taurine and methyl 4-(chloroformyl)benzoate. Both the raw materials and the products have good biodegradability, which can take into account both strong complexing ability and environmental friendliness.

[0031] (2) The method for purifying and whitening barite provided by the present invention can effectively purify and whiten barite through acid washing purification, complexation impurity removal and combined reverse flotation desiliconization process. In particular, the use of MMT-TA as a complexing agent can not only purify barite products with a whiteness of more than 92%, but also overcome the problems of existing complexing agents being difficult to degrade and lacking environmental friendliness.

[0032] (3) The method for purifying and whitening barite provided by the present invention can purify barite ore with high impurity content and low whiteness into a product with high whiteness and high purity. The entire purification and whitening process is simple and the operating conditions are mild. It has the advantages of strong raw material adaptability, low reagent consumption and relatively low energy consumption, and is suitable for industrial continuous production. Attached Figure Description

[0033] Figure 1 FTIR spectra of MMT-TA, taurine, and methyl 4-(chloroformyl)benzoate in the preparation example; Figure 2 The 1H NMR spectrum of MMT-TA in the preparation example; Figure 3 The XRD patterns are of the barite product and raw barite ore from Example 1, and analytical grade BaSO4. Detailed Implementation

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0036] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0037] The present invention will be further described below with reference to specific embodiments.

[0038] The following is information on the raw materials and instruments used in the examples. Barite ore: Originating in Wenxian County, Longnan City, Gansu Province, with a barium sulfate content of 79.7% and a whiteness of 38.2%; Taurine (TA): 99% purity, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Tannic acid: 95% purity, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; product number T834649; Barium sulfate (BaSO4): 99.9% analytical grade, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0039] Preparation Example 1 (1) 0.90 g (5 mmol) of methyl 4-carboxybenzoate (MMT) and 20 mL of toluene were added to a dry 250 mL three-necked flask. The mixture was stirred at 400 rpm under N2 atmosphere to dissolve the MMT. The flask was then cooled to 0 °C in an ice bath. 0.73 g (6 mmol) of oxaloyl chloride was slowly added dropwise at a rate of 1 drop / second. After the addition was complete, the ice bath was removed, and the mixture was stirred at 400 rpm for 4 hours at room temperature (25 °C) to induce the reaction shown in (I). Next, a small amount of sodium bicarbonate was added to the three-necked flask, and stirring was continued for 30 minutes to neutralize the generated HCl until the reaction solution was neutral. ， Subsequently, the aqueous phase was discarded after standing and separating, and the organic phase was washed with deionized water. Then, the crude product was obtained by rotary evaporation at 50-60°C and recrystallized with a mixture of ethanol and water (volume ratio of 1:1) to obtain high-purity methyl 4-chloroformylbenzoate (MMT-CL).

[0040]

[0041] MMTMMT-CL (I) (2) Weigh 0.99 g (5 mmol) of methyl 4-chloroformylbenzoate prepared in step (1) and completely dissolve it in 10 mL of ethanol to form a methyl 4-chloroformylbenzoate ethanol solution; weigh 0.688 g (5.5 mmol) of taurine (TA) and dissolve it in 10 mL of water to prepare a taurine aqueous solution; prepare a 0.01 mol / L NaOH solution. Under ice-water bath conditions, a methyl 4-chloroformylbenzoate ethanol solution was added dropwise to the taurine aqueous solution at a rate of 1 drop / second. During the addition, the pH of the reaction system was maintained at 9-10 by adding NaOH solution. After all the methyl 4-chloroformylbenzoate ethanol solution had been added, the reaction temperature was restored to 25°C, and the mixture was stirred overnight at 400 rpm, resulting in the reaction shown in (II). After the reaction was complete, the reaction solution was rotary evaporated and then vacuum dried to obtain a pale yellow solid, which is the metal ion complexing agent, denoted as MMT-TA.

[0042]

[0043] TAMMT-CLMMT-TA (II) Taurine, methyl 4-(chloroformyl)benzoate, and the prepared MMT-TA were characterized by Fourier transform infrared spectroscopy (FTIR), and the results are as follows: Figure 1 As shown: Compared to the taurine spectrum, the MMT-TA spectrum shows a position between 3500 and 3000 cm⁻¹. -1The double infrared peaks belonging to the amino group of taurine disappear and become a single peak; while at 1645 cm⁻¹... -1 1289 cm -1 The characteristic peak of secondary amide appeared at 1645 cm⁻¹. -1 The peak at 1289 cm⁻¹ belongs to the C=O peak of the amide, and is located at 1289 cm⁻¹. -1 The peak at 1730 cm⁻¹ should be the CN peak of the amide, indicating that MMT-TA has an amide structure; additionally, at 1730 cm⁻¹... -1 The peak at this point should be a characteristic peak of the ester group in the complexing agent.

[0044] The 1H NMR spectrometry of taurine, methyl 4-(chloroformyl)benzoate, and the prepared MMT-TA were characterized, and the results are as follows: Figure 2 As shown, the peak at 3.3 ppm is the water peak, the peak at 2.5 ppm is the solvent DMSO-d6 peak, the peaks at 7.9 ppm and 8.1 ppm are attributed to the 1H NMR peaks on the benzene ring, which are indicated in the structural formula. The peak at 3.89 ppm is the 1H NMR peak of the methyl group on the substituted ester group of the benzene ring. The peak at 8.7 ppm corresponds to the characteristic peak of the -NH- group of the amide bond, consistent with the predicted spectrum. Moreover, the amino peak of taurine is not present. The 1H NMR results indicate that the actual structure of MMT-TA is consistent with the designed structure.

[0045] Example 1 The following steps are used to purify and whiten barite ore: (1) Grinding and washing The raw barite ore was crushed and ground, and then passed through a 100-mesh sieve to collect the undersize material (particle size ≤150 μm). The mass m0 of the barite powder after sieving was recorded. Subsequently, the ground raw barite ore (i.e., barite powder) was countercurrently washed with deionized water to remove surface clay impurities.

[0046] (2) Acid washing and purification The barite (wet product after washing) treated in step (1) was immersed in a 3 mol / L hydrochloric acid solution, and the liquid-solid ratio was controlled at 3 mL / g (i.e., the volume of hydrochloric acid solution (mL): the mass of barite (g) = 3:1, the mass of barite is based on the dry weight after grinding and sieving, which is m0, and the mass of barite mentioned below is the same as here). The solution was heated to 80℃ and stirred for 4 hours. After the acid washing was completed, the acid washing waste liquid was separated and removed, and the solid was washed with 200% deionized water of the barite mass to obtain the acid-washed and purified barite wet material.

[0047] (3) Complexation to remove impurities Add deionized water and complexing agent MMT-TA to the barite wet material obtained in step (2) to form a complexing slurry, so that the mass ratio of MMT-TA to barite in the complexing slurry is 0.5:10 and the concentration of MMT-TA is 0.01 g / mL. Add sodium carbonate to adjust the pH of the complexing slurry to 5. Then, heat to 50°C and stir at 200 rpm for 6 hours to complex. After the reaction is completed, filter and wash.

[0048] (4) Reverse flotation for silicon removal Take the product obtained in step (3), sodium stearate (collector), tannic acid (inhibitor) and deionized water, and prepare a slurry according to the ratio of 10g barite, 0.8g sodium stearate, 0.1g tannic acid and 50ml deionized water (in the slurry, the mass ratio of barite to tannic acid is 100:1, the mass ratio of barite to sodium stearate is 100:8, and the mass-volume ratio of barite to deionized water is 1g:5mL). After ultrasonic dispersion at 100W, react for 6 hours at 60℃ and 200rpm. After standing, discard the upper suspension to obtain the lower solid. Repeat the reverse flotation operation three times (re-adding collector, inhibitor and deionized water to the lower solids) to remove quartz and dry the lower solids.

[0049] (5) Calcination treatment The product obtained in step (4) was calcined at 800°C for 2 hours at a heating rate of 3°C / min, and then naturally cooled to obtain the final product—barite. The whiteness of the barite product after purification and whitening in this embodiment was measured to be 94.3% using a visible light spectrophotometer.

[0050] X-ray diffraction (XRD) was performed on the raw barite ore, analytical grade barium sulfate, and the purified and whitened barite product of this example. The results are as follows: Figure 3 As shown: Compared to raw barite ore ( Figure 3 The abbreviation for "raw ore" is used in this embodiment. The purified and whitened barite product ( Figure 3 The XRD pattern of the purified barite product (abbreviated as "purified") shows fewer impurity peaks, such as those at 2θ=29.5° and those between 2θ=26~27°, which have disappeared or weakened in intensity. A comparison is made between the purified and whitened barite product of this embodiment and analytical grade barium sulfate (…). Figure 3 The XRD patterns of the barite (abbreviated as "BaSO4") show that the peak positions and intensities are basically the same, indicating that the purity of the barite product after purification and whitening in this embodiment is high. The content of BaSO4 in the barite product obtained in this embodiment is about 95% based on the peak area.

[0051] Example 2 The only difference between this embodiment and embodiment 1 is the calcination temperature in step (5). The calcination temperature in step (5) of this embodiment is 700°C. The whiteness of the barite product obtained by purification in this embodiment is 92.3% and the purity is 94.2%.

[0052] Example 3 The only difference between this embodiment and embodiment 1 is the calcination temperature in step (5). The calcination temperature in step (5) of this embodiment is 900°C. The whiteness of the barite product obtained by purification in this embodiment is 94.1% and the purity is 95.1%.

[0053] Example 4 The only difference between this embodiment and embodiment 1 is the calcination temperature in step (5). The calcination temperature in step (5) of this embodiment is 1000℃. The whiteness of the barite product obtained by purification in this embodiment is 94.8% and the purity is 95.5%.

[0054] Comparative Example 1 The only difference between this comparative example and Example 1 is that steps (3) to (4) are omitted in this comparative example. That is, this comparative example does not perform complexation to remove impurities and reverse flotation to remove silicon. The whiteness of the barite product obtained by this comparative example is 46.2% and the purity is 83.3%.

[0055] Comparative Example 2 The only difference between this comparative example and Example 1 is that step (3) is omitted in this comparative example. That is, this comparative example does not perform complexation to remove impurities. The whiteness of the barite product obtained by this comparative example is 88.4% and the purity is 88.7%.

[0056] Comparative Example 3 The only difference between this comparative example and Example 1 is the complexing agent used in step (3). In this comparative example, oxalic acid is used instead of MMT-TA in step (3) of Example 1. The whiteness and purity of the barite product obtained by this comparative example are 89.7%.

[0057] Comparative Example 4 The only difference between this comparative example and Example 1 is the complexing agent used in step (3). In this comparative example, EDTA-2Na is used instead of MMT-TA in step (3) of Example 1. The whiteness of the barite product obtained by this comparative example is 91.4% and the purity is 90.2%.

[0058] Comparative Example 5 The only difference between this comparative example and Example 1 is the complexing agent used in step (3). In this comparative example, vitamin C (ascorbic acid) is used instead of MMT-TA in step (3) of Example 1. The whiteness of the barite product obtained by purification in this comparative example is 89.3% and the purity is 89.1%.

[0059] Comparative Example 6 The only difference between this comparative example and Example 1 is that step (4) is omitted in this comparative example. That is, this comparative example does not perform reverse flotation to remove silicon. The whiteness of the barite product obtained by this comparative example is 57.1% and the purity is 85.1%.

[0060] Comparative Example 7 The only difference between this comparative example and Example 1 is the mass ratio of barite to sodium stearate in the slurry prepared in step (4). In this comparative example, the mass ratio of barite to sodium stearate in step (4) is 100:2.

[0061] The whiteness of the barite product obtained by this comparative purification was 72.1%, and the purity was 86.2%.

[0062] Comparative Example 8 The only difference between this comparative example and Example 1 is the calcination time in step (5). The calcination time in step (5) of this comparative example is 1 hour. The whiteness of the barite product obtained by this comparative example is 79.8% and the purity is 92.7%.

[0063] As can be seen from the results of Example 1 and Comparative Examples 1-6, steps (3) and (4) are crucial steps affecting the whiteness of the final barite product and cannot be omitted. Furthermore, the complexing agent MMT-TA selected in this invention has a better complexing effect than traditional complexing agents such as oxalic acid, EDTA-2Na, and vitamin C, resulting in higher whiteness and purity of the obtained barite product. Moreover, compared to EDTA-2Na, which has a better complexing effect than traditional complexing agents, the complexing agent MMT-TA not only produces a barite product with higher whiteness and purity and can replace EDTA-2Na, but also has better biodegradability (MMT-TA uses biodegradable taurine as a raw material, and MMT-TA has an amide structure, also exhibiting good biodegradability, while EDTA-2Na is difficult to degrade), making it more environmentally friendly.

[0064] As can be seen from the results of Example 1 and Comparative Examples 6 and 7, if the mass ratio of barite to sodium stearate in step (4) is not within the range required by the present invention, it is difficult to achieve the purpose of effectively purifying and whitening barite.

[0065] As can be seen from the results of Examples 1-4 and Comparative Example 8, calcination temperature and time affect the whiteness of the final barite product. The calcination time needs to be more than 2 hours and the calcination temperature needs to be between 800℃ and 1000℃. The increase in temperature does not significantly increase the whiteness of the final product. Based on economic considerations, the preferred calcination temperature is 800℃ to 900℃.

[0066] In summary, by selecting suitable complexing agents, optimizing the concentration and dosage of hydrochloric acid solution in pickling, adjusting the ratio of barite to collector and inhibitor in reverse flotation for silicon removal, and adjusting the calcination temperature, this invention not only effectively improves the whiteness of barite products but also achieves the goals of environmental friendliness and relatively reduced energy consumption.

[0067] The above description provides an illustrative overview of the present invention and its embodiments. This description is not restrictive, and the embodiments shown are merely one example of the invention's implementation. Actual implementations are not limited to these examples. Therefore, if those skilled in the art are inspired by this description and design similar implementations and examples without departing from the spirit of the invention, such designs should fall within the scope of protection of the present invention.

Claims

1. A complexing agent, characterized in that, The structural formula of the complexing agent is shown in formula a: 。 2. The application of the complexing agent as described in claim 1 in the purification and whitening of barite, characterized in that, The mass ratio of the complexing agent to the barite is (0.1~0.5):

10.

3. A method for purifying and whitening barite, characterized in that, Includes the following steps: (1) Provide barite after crushing and grinding, and wash the barite with deionized water; (2) The wet product obtained in step (1) is immersed in an inorganic acid solution and stirred at 30~80℃ for 3~6 hours. After the reaction, the solid and liquid are separated and washed with water to obtain the acid-washed and purified barite wet material. (3) Provide a slurry containing the barite wet material, deionized water and complexing agent, adjust the pH value of the slurry to 5-6, stir and complex at 50-80°C for 4-10 hours, and then filter and wash. (4) Provide a mixed slurry containing the product obtained in step (3), a collector, an inhibitor and deionized water, and after ultrasonic dispersion, react for 6 to 12 hours at 40 to 80°C and 200 to 500 rpm. After the reaction is completed, let it stand, separate and discard the upper suspension, and dry the lower solid. (5) The dried solid is calcined at high temperature to obtain the purified and whitened barite product; The structure of the complexing agent mentioned in step (3) is shown in formula a: 。 4. The method for purifying and whitening barite according to claim 3, characterized in that, In step (1), the particle size of the barite after crushing and grinding is less than or equal to 150 μm.

5. The method for purifying and whitening barite according to claim 4, characterized in that, In step (2), the inorganic acid includes one or both of hydrochloric acid and nitric acid; The concentration of the inorganic acid solution is 1~4 mol / L; The amount of inorganic acid solution used is controlled so that the liquid-solid ratio of inorganic acid solution to barite is 2~5 mL / g.

6. The method for purifying and whitening barite according to claim 3 or 5, characterized in that, In step (3), the mass ratio of the complexing agent to barite in the slurry to be complexed is (0.1~0.5):10; The barite contains 75-90% barium sulfate. The concentration of the complexing agent in the slurry to be complexed is 0.005~0.02 g / mL.

7. The method for purifying and whitening barite according to any one of claims 3 to 6, characterized in that, In step (3), the pH value of the slurry system to be complexed is adjusted by adding one or more of NaOH, Na2CO3, and NaHCO3; In step (4), the collector includes one or more of sodium stearate, sodium oleate, sodium hexadecyl sulfate, and sodium hexametaphosphate; In step (4), the inhibitor includes one or more of tannic acid, glucose, and cyclodextrin.

8. The method for purifying and whitening barite according to claim 7, characterized in that, In step (4), the mass ratio of barite to inhibitor in the slurry is 100:(0.8~1.2). The mass ratio of barite to collector in the slurry is 100:(7~15).

9. The method for purifying and whitening barite according to claim 8, characterized in that, In step (4), the mass-to-volume ratio of barite to deionized water in the slurry is 1 g: (5~10) mL.

10. The method for purifying and whitening barite according to claim 3 or 9, characterized in that, In step (5), the conditions for high-temperature calcination are to heat the temperature to 700-1100℃ at a heating rate of 2-4℃ / min and hold the temperature for 2-4 hours.

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