Method for purifying impurity metal ions in coal dressing water

Abstract

The invention relates to a method for purifying impurity metal ions in coal dressing water, and belongs to the technical field of wastewater treatment. Comprising the following steps: (1) precipitating; (2) filtering; (3) extracting; (4) liquid separation; wherein in the step (1), a precipitator is added into the coal dressing water, and metal ions in the coal dressing water are settled; the precipitant is selected from at least one of silicate, fluosilicate and metaphosphate; in the step (3), an extracting agent is added into the filtered coal dressing water to further extract impurity ions; the extracting agent is selected from at least one of phosphate ester or primary amine. According to the method, clean and efficient removal of impurity metal ions is achieved by adjusting the conditions of chemical precipitation, chemical agent type and dosage of solution extraction, reaction temperature, reaction time, stirring strength and the like for coal dressing water with different components.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for purifying impure metal ions in coal preparation water. Background Art

[0002] At present, harmful metal ions are inevitably produced or introduced in the process of coal mining, which seriously affects the subsequent comprehensive recycling and utilization. At the same time, with the continuous development and utilization of coal resources, high-quality coal resources have been exhausted, and complex low-grade coal resources have become the main body of mineral processing. Impurity metal ions increase the difficulty of coal resource sorting. This impurity metal ion has the greatest impact in the slurry / solution system, changing the rheological properties of the slurry, hindering the interaction between mineral processing agents and minerals, affecting the reuse and discharge of coal processing water, and restricting the sustainable development and utilization of coal resources.

[0003] Faced with increasingly severe problems such as the complex composition and difficulty in recycling of coal preparation water, efficient purification and utilization of coal preparation water has become one of the important directions for the sustainable development of coal preparation plants. The selective removal of impurity metal ions such as iron, magnesium, and aluminum in coal preparation water has long been a difficult problem in purification technology research. Among traditional treatment methods, the treatment capacity of chemical methods is relatively limited, and it is difficult to reuse the treated products; the membrane exchange method needs to rely on additional membrane exchange equipment, with high treatment costs and complex operations. Therefore, the development and application of impurity metal ion purification technology in coal preparation water is imminent.

[0004] Traditional purification methods are limited to industrial water treatment methods, while ignoring the mineral resource characteristics of coal resources. Based on the comprehensive recovery and utilization of mineral resources, mineral sorting is combined with chemical engineering to develop impurity metal ion purification technology in coal preparation water to efficiently remove impurity metal ions such as iron, magnesium, and aluminum, realize coal preparation water purification and reuse, low-standard discharge, reduce the loss and waste of coal resources, and have dual significance for the comprehensive recovery and utilization of coal resources and environmental protection. Summary of the invention

[0005] In view of the problems of low processing capacity and high cost in the existing coal preparation water treatment, the present invention provides a method for purifying impure metal ions in coal preparation water. The impurity metal ions in the coal preparation water are removed by combining chemical precipitation with solution extraction to achieve the purpose of product purification.

[0006] The technical solution of the present invention is as follows: A method for purifying impure metal ions in coal preparation water comprises the following steps: (1) precipitation; (2) filtration; (3) extraction; (4) separation; wherein, In step (1), a precipitant is added to the coal preparation water to precipitate the metal ions in the coal preparation water; the precipitant is selected from at least one of silicate, fluorosilicate and metaphosphate; In step (3), an extractant is added to the filtered coal preparation water to further extract the impurity ions; the extractant is selected from at least one of phosphate esters and primary amines.

[0007] Furthermore, the impurity metal ions in the coal preparation water include Fe 3+ Mg 2+ 、Al 3+ At least one of .

[0008] Furthermore, the precipitant is selected from sodium silicate, sodium fluorosilicate or sodium hexametaphosphate.

[0009] Furthermore, the phosphate ester is selected from tributyl phosphate or dioctyl phosphate.

[0010] Furthermore, the primary amine is selected from dodecyl primary amine or octadecyl primary amine.

[0011] Furthermore, in step (1), the amount of precipitant used is 3-10 kg / t based on the mass of the coal preparation water to be treated; the reaction time is 3-10 min; the reaction temperature is 40-60° C.; and the stirring speed is 300-800 r / min.

[0012] Furthermore, in step (3), the amount of extractant used is 5-15 kg / t based on the mass of the coal preparation water to be treated; the extraction time is 10-20 min; the extraction temperature is 35° C.-55° C.; and the oscillation intensity is 100-300 times / min.

[0013] The beneficial effects of the present invention are: The present invention aims at coal preparation water with different components, and realizes the removal of impurity metal ions by adjusting the type and dosage of chemical precipitation and solution extraction reagents, reaction temperature, reaction time, stirring intensity and other conditions. Since there are many types of coal preparation water, the method of chemical precipitation alone has a faster reaction time and has a certain effect when the content of impurity metal ions is high, but the effect is not good when the content is low; the method of solvent extraction alone has a certain effect when the content of impurity metal ions is low, but the reaction time is long and it is greatly affected by the system. Therefore, combining the advantages of the two methods, a coal preparation water purification method of chemical precipitation-solution extraction is developed to realize the clean and efficient removal of impurity metal ions. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0015] Example 1 Taking the coal preparation water of a coal preparation plant in Shandong as the research object, the impurity metal ion purification treatment was carried out as follows: (1) Precipitation The coal preparation water is introduced into the sedimentation tank. Sodium fluorosilicate is selected as the precipitant. The dosage is 3kg / t, 5kg / t, 8kg / t and 10kg / t respectively according to the weight of the coal preparation water to be purified. After the precipitant is added to the coal preparation water, the reaction is stirred for 5 minutes. The reaction temperature is 45°C and the stirring speed is 500r / min.

[0016] (2) Filtering The settled coal preparation water is pressed into the mine backwash filtration equipment for filtration, and the filtrate enters the extraction tank.

[0017] (3) Extraction Add dioctyl phosphate to the extraction tank. The amount of dioctyl phosphate added is selected according to the weight of the coal-washing water to be purified, and 3kg / t, 5kg / t, 8kg / t and 10kg / t are selected respectively. After adding dioctyl phosphate, the extraction temperature is controlled at 45°C, the extraction time is 15min, and the shaking intensity is 300 times / min. After the shaking is completed, let it stand.

[0018] (4) Liquid separation The liquid after standing is separated, the coal preparation water is sampled and tested, and the extractant enters the regeneration tank for regeneration and can be used as the subsequent extractant. The ion content of the coal preparation water treated with different amounts of precipitant and extractant is tested, and the specific results are shown in Table 1: Table 1- Results of a coal preparation water purification and impurity removal test in Shandong

[0019] From the results in Table 1, it can be seen that with the increase in the dosage of the reagent, the content of impurity metal ions such as iron, magnesium, and aluminum decreased sharply. Under the condition that the dosage of sodium fluorosilicate and dioctyl phosphate was 8 kg / t, the content of impurity metal ions such as iron, aluminum, and magnesium decreased to 0.70%, 1.54%, and 1.52%. This result fully demonstrates that the synergistic effect of sodium fluorosilicate chemical precipitation and dioctyl phosphate solution extraction can complete the purification and impurity removal of the mineral processing water.

[0020] Example 2 Taking the return water of a coal preparation plant in Guizhou as the research object, the impurity metal ion purification treatment was carried out as follows: (1) Precipitation The coal-washing water is introduced into the sedimentation tank, and sodium hexametaphosphate is selected as the precipitant, and the amount used is 3kg / t based on the weight of the coal-washing water to be purified; after the precipitant is added to the coal-washing water, the reaction is stirred for 10 minutes, the reaction temperature is 40°C, and the stirring speed is 300r / min.

[0021] (2) Filtering The settled coal preparation water is pressed into the mine backwash filtration equipment for filtration, and the filtrate enters the extraction tank.

[0022] (3) Extraction Add dibutyl phosphate to the extraction tank. The amount of dibutyl phosphate added is selected according to the weight of the coal-washing water to be purified, and the weight is 0.5kg / t, 1.0kg / t, 1.5kg / t, 2.0kg / t, 2.5kg / t, 3.0kg / t and 5.0kg / t respectively. After the extraction agent is added, the extraction temperature is controlled at 40°C, the extraction time is 20min, and the shaking intensity is 300 times / min. After the shaking is completed, let it stand.

[0023] (4) Liquid separation The liquid after standing is separated, the coal preparation water is sampled and tested, and the extractant enters the regeneration tank for regeneration and can be used as the subsequent extractant. The ion content of the coal preparation water treated with different amounts of precipitant and extractant is tested, and the specific results are shown in Table 2: Table 2- Results of a coal preparation water purification and impurity removal test in Guizhou

[0024] From the results in Table 2, it can be seen that sodium hexametaphosphate and dibutyl phosphate work synergistically to improve the removal efficiency of impurity metal ions. When the dosage of sodium hexametaphosphate is 3kg / t and the dosage of dibutyl phosphate is 5.0kg / t, the impurity metal ions of iron, aluminum and magnesium are reduced to 0.52%, 1.62% and 1.50% respectively. This result shows that the chemical precipitation of sodium hexametaphosphate and the extraction of dibutyl phosphate solution can achieve the purification and reuse of the mineral processing return water.

[0025] Example 3 Taking the coal preparation water of a coal preparation plant in Shanxi as the research object, the impurity metal ion purification treatment was carried out as follows: (1) Precipitation The coal preparation water is introduced into the sedimentation tank, and sodium silicate is selected as the precipitant, and the amount used is 12kg / t based on the weight of the coal preparation water to be purified; after the precipitant is added to the coal preparation water, the reaction is stirred for 8 minutes, and the reaction temperatures are 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃ and 60℃ respectively, and the stirring speed is 600r / min.

[0026] (2) Filtering The settled coal preparation water is pressed into the mine backwash filtration equipment for filtration, and the filtrate enters the extraction tank.

[0027] (3) Extraction Add dodecyl primary amine to the extraction tank, the amount of which is 12kg / t based on the weight of the coal-washing water to be purified; after the extractant is added, the extraction temperature is controlled to be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C and 60°C, the extraction time is 20min, and the shaking intensity is 300 times / min. After the shaking is completed, let it stand.

[0028] (4) Liquid separation The liquid after standing is separated, the coal preparation water is sampled and tested, and the extractant enters the regeneration tank for regeneration and can be used as the subsequent extractant. The ion content of the coal preparation water treated with different amounts of precipitant and extractant is tested, and the specific results are shown in Table 3: Table 3 - Test results of coal preparation water purification and impurity removal in a coal preparation plant in Shanxi

[0029] From the results in Table 3, it can be seen that with the increase of temperature, the content of the three impurity metal ions shows a trend of decreasing first and then increasing, reaching the minimum value in the temperature range of 45-55°C. This result shows that the synergistic effect of sodium silicate chemical precipitation and dodecyl primary amine solution extraction can effectively achieve the purification and impurity removal of the coal slime dressing water.

[0030] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A method for purifying impurity metal ions in coal preparation water, characterized in that: The steps include: (1) precipitation; (2) filtration; (3) extraction; (4) separation; wherein, In step (1), a precipitant is added to the coal preparation water to precipitate the metal ions in the coal preparation water; the precipitant is selected from at least one of silicate, fluorosilicate and metaphosphate; In step (3), an extractant is added to the filtered coal preparation water to further extract the impurity ions; the extractant is selected from at least one of phosphate esters and primary amines.

2. A method for purifying impurity metal ions in coal preparation water according to claim 1, characterized in that: Impurity metal ions in coal preparation water include Fe 3+ Mg 2+ 、Al 3+ At least one of .

3. A method for purifying impurity metal ions in coal preparation water according to claim 1, characterized in that: The precipitating agent is selected from sodium silicate, sodium fluorosilicate or sodium hexametaphosphate.

4. A method for purifying impure metal ions in coal preparation water according to claim 1, characterized in that: The phosphate ester is selected from tributyl phosphate or dioctyl phosphate.

5. A method for purifying impure metal ions in coal preparation water according to claim 1, characterized in that: The primary amine is selected from dodecyl primary amine or octadecyl primary amine.

6. A method for purifying impure metal ions in coal preparation water according to claim 1, characterized in that: In step (1), the amount of precipitant is 3-10 kg / t based on the mass of the coal preparation water to be treated; the reaction time is 3-10 min; the reaction temperature is 40-60 ° C; and the stirring speed is 300-800 r / min.

7. A method for purifying impure metal ions in coal preparation water according to claim 1, characterized in that: In step (3), the amount of extractant used is 5-15 kg / t based on the mass of the coal preparation water to be treated.

8. A method for purifying impure metal ions in coal preparation water according to claim 1, characterized in that: The extraction time is 10~20min; the extraction temperature is 35℃~55℃; the shaking intensity is 100~300 times / min.

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