Treatment method of slime water

Abstract

The present invention provides a method for treating coal slime water. The method includes naturally settling the coal slime water for 6 - 8 hours to obtain primary settled coal slime water, adding a first microbial flocculant containing a fermentation extract of Bacillus subtilis and yeast extract to obtain secondary settled coal slime water, adding a second microbial flocculant containing Aspergillus fumigatus to obtain tertiary settled coal slime water, and filtering and discharging it into a clear water tank. Yeast extract and the fermentation extract of Bacillus subtilis in the first microbial flocculant of the present invention contain a large amount of components such as proteins and polysaccharides, which have good flocculation effects on fine particulate matter and clay minerals in the coal slime water. And adding the second microbial flocculant containing Aspergillus fumigatus to enhance its flocculation and sedimentation effect on fine particulate matter, further improving the flocculation effect of the coal slime water, enabling the combustible substances in the coal slime water to be fully recycled, further reducing costs, and greatly shortening the sedimentation time.

Description

Technical Field

[0001] The present invention relates to the technical field of coal slime water purification, and in particular, to a method for treating coal slime water. Background Art

[0002] Coal is the most important energy source in China, accounting for 76% in the primary energy consumption structure. Coal is also a non-clean energy source, and beneficiation and processing are required to reduce the content of minerals and harmful impurities in it as much as possible. Coal slime water has become one of the main pollution sources in the coal industry, and treatment is urgent. Coal slime water is the industrial tail water formed by wet coal washing, which contains a large amount of coal slime particles and is one of the main pollution sources in coal mines. Coal slime water is a complex multi-dispersed system. It is composed of some particles with different particle sizes, shapes, densities, lithologies, etc., mixed in different proportions.

[0003] Coal mine coal slime water can be divided into two categories: one is generated during the washing of raw coal with a relatively short geological age, high ash content and high impurity content; the other is generated during the washing of raw coal with a relatively long geological age and good coal quality. In order to avoid the pollution of water environment by suspended solids and residual agents in coal slime water and affect the growth of animals and plants, coal preparation plants generally used to directly discharge coal slime water into coal slime sedimentation tanks for natural sedimentation, and the treated clarified water was recycled. This method does not require the addition of chemical agents and greatly reduces the product cost. However, with the development of technology and the improvement of coal mining mechanization, the content of fine coal in the raw coal selected has increased, which has brought difficulties to the treatment of coal slime water. It often takes several days or even months for a large number of fine particles in coal slime water to settle completely. Summary of the Invention

[0004] The main object of the present invention is to provide a method for treating coal slime water to solve the problems of poor treatment effect and high process cost of coal slime water in the prior art.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided a method for treating coal slime water. The coal slime water contains fine particulate matter and clay minerals. The treatment method includes the following steps: Step S1, naturally sedimenting the coal slime water for 6 - 8 hours to obtain primary sedimented coal slime water; Step S2, adding a first microbial flocculant to the primary sedimented coal slime water and adjusting the pH of the primary sedimented coal slime water to 6.0 - 8.0 to obtain secondary sedimented coal slime water; Step S3, adding a second microbial flocculant to the secondary sedimented coal slime water to obtain tertiary sedimented coal slime water, and filtering and discharging it into a clear water tank; wherein, the first microbial flocculant includes a fermentation extract of Bacillus subtilis and yeast extract, and the second microbial flocculant includes Aspergillus fumigatus.

[0006] Further, in the first microbial flocculant, the mass ratio of the fermentation extract of Bacillus subtilis to yeast extract is 2:(0.5 - 1).

[0007] Further, the volume ratio of the first microbial flocculant to the primary sedimentation coal slurry water is (2 - 20):100.

[0008] Further, the volume ratio of the second microbial flocculant to the secondary sedimentation coal slurry water is (3 - 15):100.

[0009] Further, before adding the first microbial flocculant, step S2 further includes the step of adding a coagulant aid solution to the primary sedimentation coal slurry water, and the coagulant aid includes bone glue and sodium alginate.

[0010] Further, the mass ratio of bone glue to sodium alginate is 1:(10 - 30).

[0011] Further, the mass fraction of the coagulant aid solution is 1.5 - 2.5%; preferably, the volume ratio of the coagulant aid solution to the primary sedimentation coal slurry water is 1:(50 - 70).

[0012] Further, the fermentation extract of Bacillus subtilis is obtained by the following method: inoculating the Bacillus subtilis seed culture solution into a culture medium, performing aerobic fermentation to obtain a fermentation broth; filtering the fermentation broth, and subjecting the filtrate to evaporation and concentration to obtain the fermentation extract of Bacillus subtilis.

[0013] Further, the temperature of the aerobic fermentation is 30 - 32 °C, the rotation speed is 120 - 240 rpm, and the time is 2 - 4 days.

[0014] Further, the culture conditions of Aspergillus fumigatus include: temperature 30 - 32 °C, pH 5.5 - 7.5, time 2 - 7 days, and the bacterial liquid concentration is (8 - 10)×10 7 CFU / mL.

[0015] Applying the technical solution of the present invention, adding the first microbial flocculant to the coal slurry water after short - time natural sedimentation, the yeast extract and the fermentation extract of Bacillus subtilis in it contain a large amount of components such as proteins and polysaccharides, which have a good flocculation effect on the fine particulate matter and clay minerals in the coal slurry water, and adding the second microbial flocculant containing Aspergillus fumigatus to enhance its flocculation and sedimentation effect on the fine particulate matter, further improving the flocculation effect of the coal slurry water. The present invention uses different microbial flocculants to flocculate the fine particulate matter and clay minerals in the coal slurry water, enabling the full recovery and utilization of combustibles in the coal slurry water and greatly shortening the sedimentation time. In addition, the addition of microbial flocculants can avoid the use of inorganic or organic flocculants, effectively prevent environmental pollution, and reduce the cost of coal slurry water treatment. Detailed Embodiments

[0016] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0017] It should be noted that, unless otherwise specified, the materials used in the present invention can be conveniently obtained from the market.

[0018] Term Explanation:

[0019] Yeast extract: A substance refined by degrading proteins, nucleic acids, etc. inside yeast cells using technologies such as autolysis, enzymatic hydrolysis, separation, and concentration with edible yeast as the raw material, which can be conveniently obtained from the market.

[0020] As described in the background art of the present invention, there are problems of poor slime water treatment effect and high process cost in the prior art. To solve the above problems, in a typical embodiment of the present invention, a method for treating slime water is provided. The slime water contains fine particulate matter and clay minerals. The treatment method includes the following steps: Step S1, naturally sediment the slime water for 6 - 8 h to obtain primary sedimented slime water; Step S2, add a first microbial flocculant to the primary sedimented slime water and adjust the pH of the primary sedimented slime water to 6.0 - 8.0 to obtain secondary sedimented slime water; Step S3, add a second microbial flocculant to the secondary sedimented slime water to obtain tertiary sedimented slime water, and then filter and discharge it into a clear water tank; wherein, the first microbial flocculant includes a fermentation extract of Bacillus subtilis and yeast extract, and the second microbial flocculant includes Aspergillus fumigatus.

[0021] The fine particulate matter is mainly slime particulate matter with a mineral particle size less than 18 μm or less than 10 μm. The clay minerals are mainly kaolinite, illite, and montmorillonite. Their special crystal structures make them easily slime or be cracked by mechanical impact to form a large number of micron-sized fine particles during the wet beneficiation of coal, making it difficult to settle. In the present invention, the slime water is first discharged into a primary sedimentation tank, and after a short natural sedimentation of 6 - 8 hours, the large impurities in it are removed, and then the slime water after primary sedimentation treatment is discharged into an adjustment tank; the slime particles sedimented at the bottom of the primary sedimentation tank are collected and subjected to pressure filtration treatment, and the sewage obtained by pressure filtration is returned to the primary sedimentation tank and then subjected to adjustment, filtration, and other treatments. Then, a first microbial flocculant including a fermentation extract of Bacillus subtilis and yeast extract is added to the adjustment tank, stirred, and the pH of the slime water is adjusted to 6.0 - 8.0 to provide a suitable pH environment for the microbial flocculant to flocculate and sediment the slime water. Among them, the yeast extract contains components such as glucan, mannan, protein, and N-acetylglucosamine, and the fermentation extract of Bacillus subtilis contains protein, polysaccharide, as well as a small amount of nucleic acid and other substances, which have a good flocculation effect on the fine particulate matter and clay minerals in the slime water.

[0022] Finally, a second microbial flocculant containing Aspergillus fumigatus is added to the regulating tank to enhance the flocculation and sedimentation effect of the first microbial flocculant on fine particulate matter, further improve the flocculation effect of coal slime water, so that the coal slime water is flocculated and sedimented again. The coal slime water after the second flocculation and sedimentation is filtered by a filtering device and then discharged into a clear water tank. The sedimented coal slime particles are collected separately and then subjected to pressure filtration. The sewage obtained by pressure filtration is returned to the regulating tank and then filtered and other treatments are carried out. The filtration includes conventional steps such as coarse grid, microfiltration, and ultrafiltration. The present invention uses different microbial flocculants to flocculate fine particulate matter and clay minerals in coal slime water respectively, which can fully recover and utilize the combustibles in coal slime water and greatly shorten the sedimentation time. In addition, the addition of microbial flocculants can avoid the use of inorganic or organic flocculants, effectively prevent environmental pollution, reduce the cost of coal slime water treatment, and the microbial flocculants are highly biodegradable, environmentally friendly, do not produce secondary pollution, and do not affect the growth of animals and plants.

[0023] To further improve the flocculation effect of coal slime water, in a preferred embodiment, in the first microbial flocculant, the mass ratio of the fermentation extract of Bacillus subtilis to yeast extract is 2:(0.5 - 1). Typically but not limitedly, the mass ratio of the fermentation extract of Bacillus subtilis to yeast extract is 2:0.5, 2:0.6, 2:0.7, 2:0.8, 2:0.9, 2:1 or the range value composed of any two of these ratios.

[0024] In a preferred embodiment, the volume ratio of the first microbial flocculant to the primary sedimented coal slime water is (2 - 20):100. The addition ratio of the first microbial flocculant includes but is not limited to the above range. When within the above range, it has a better flocculation effect on the fine particulate matter and clay minerals in coal slime water, and there is no need to add too much flocculant to cause cost increase. Typically but not limitedly, the volume ratio of the first microbial flocculant to the primary sedimented coal slime water is 2:100, 5:100, 10:100, 12:100, 15:100, 20:100 or the range value composed of any two of these ratios.

[0025] Correspondingly, in a preferred embodiment, the volume ratio of the second microbial flocculant to the secondary sedimented coal slime water is (3 - 15):100. The addition ratio of the second microbial flocculant includes but is not limited to the above range. When within the above range, it has a better auxiliary flocculation effect on the first microbial flocculant, and there is no need to add too much flocculant to cause cost increase. Typically but not limitedly, the volume ratio of the second microbial flocculant to the secondary sedimented coal slime water is 3:100, 6:100, 9:100, 12:100, 15:100 or the range value composed of any two of these ratios.

[0026] To further enhance the flocculation and sedimentation effect of the first microbial flocculant on fine particulate matter, in a preferred embodiment, before adding the first microbial flocculant, step S2 further includes the step of adding a coagulant aid solution to the primary sedimentation coal slurry water. The coagulant aid includes bone glue and sodium alginate. After the above coagulant aid is added to the coal slurry water, it can adsorb and bond the fine coal particles in the coal slurry water to form larger coal slag precipitates, thereby further improving the treatment effect of the coal slurry water.

[0027] In a preferred embodiment, the mass ratio of bone glue to sodium alginate is 1:(10 - 30), which can further assist in improving the flocculation effect of the coal slurry water. Typically but not limited to, the mass ratio of bone glue to sodium alginate is 1:10, 1:15, 1:20, 1:25, 1:30 or the range values composed of any two of these ratios.

[0028] The addition amount of the coagulant aid can be adjusted according to the treatment situation of the coal slurry water. In a preferred embodiment, the mass fraction of the coagulant aid solution is 1.5 - 2.5%; preferably, the volume ratio of the coagulant aid solution to the primary sedimentation coal slurry water is 1:(50 - 70), which can improve the auxiliary flocculation effect and further reduce the cost at the same time. Typically but not limited to, the volume ratio of the coagulant aid solution to the primary sedimentation coal slurry water is 1:50, 1:55, 1:60, 1:65, 1:70 or the range values composed of any two of these ratios.

[0029] For the purpose of having more flocculation active ingredients such as glucan, mannan, protein, and N-acetylglucosamine in the Bacillus subtilis fermentation extract, thereby further improving the flocculation effect of the microbial flocculant in the present invention on fine particulate matter and clay minerals in the coal slurry water, in a preferred embodiment, the Bacillus subtilis fermentation extract is obtained by the following method: inoculating the Bacillus subtilis seed culture solution in a culture medium and performing aerobic fermentation to obtain a fermentation broth; filtering the fermentation broth and evaporating and concentrating the filtrate to obtain the Bacillus subtilis fermentation extract.

[0030] To further improve the acquisition rate of the Bacillus subtilis fermentation extract, in a preferred embodiment, the temperature of the aerobic fermentation is 30 - 32 °C, the rotation speed is 120 - 240 rpm, and the time is 2 - 4 days.

[0031] In a preferred embodiment, the culture conditions of Aspergillus fumigatus include: temperature 30 - 32 °C, pH 5.5 - 7.5, time 2 - 7 days, and the bacterial liquid concentration is (8 - 10)×10 7 CFU / mL, so that more Aspergillus fumigatus can be obtained in a short time to assist the first microbial flocculant in the flocculation and sedimentation of fine particulate matter.

[0032] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0033] Example 1

[0034] A method for treating coal slime water includes the following steps:

[0035] Step 1: Drain the coal slime water into the primary sedimentation tank, let it settle naturally for 6 hours, and then drain the coal slime water after primary sedimentation treatment into the adjustment tank; the coal slime particles settled at the bottom of the primary sedimentation tank are collected and subjected to pressure filtration, and the sewage obtained by pressure filtration is continuously drained into the primary sedimentation tank and then subjected to adjustment, filtration and other treatments; before the primary sedimentation coal slime water is drained into the adjustment tank, it also includes flotation treatment;

[0036] Step 2: Add the first microbial flocculant into the adjustment tank, stir and adjust the pH of the coal slime water to 6.0, and the coal slime water undergoes flocculation sedimentation to obtain the secondary sedimentation coal slime water;

[0037] Step 3: Add the second microbial flocculant into the secondary sedimentation coal slime water, and the coal slime water undergoes flocculation sedimentation again to obtain the tertiary sedimentation coal slime water, which is filtered by a filtration device and then drained into the clear water tank; the settled coal slime particles are respectively collected and subjected to pressure filtration, and the sewage obtained by pressure filtration is continuously drained into the adjustment tank and then subjected to filtration and other treatments;

[0038] Among them, the volume ratio of the first microbial flocculant to the coal slime water is 2:100, the first microbial flocculant is the fermentation extract of Bacillus subtilis and yeast extract, and the mass ratio of the two is 2:0.5; the second microbial flocculant is Aspergillus fumigatus, and the volume ratio to the coal slime water is 3:100; a coagulant aid is added before adding the first microbial flocculant into the adjustment tank, and the coagulant aid is an aqueous solution of bone glue and sodium alginate with a mass fraction of 1.5%, the mass ratio of bone glue to sodium alginate is 1:10, and the mass ratio of the coagulant aid to the coal slime water is 1:50.

[0039] Among them, the fermentation extract of Bacillus subtilis: Inoculate the seed culture solution of Bacillus subtilis in the medium, and carry out aerobic fermentation for 2 - 4 days at a temperature of 30°C and a rotation speed of 120 revolutions per minute, filter the obtained fermentation broth, and evaporate and concentrate the filtrate to obtain the fermentation extract of Bacillus subtilis.

[0040] Among them, the cultivation of Aspergillus fumigatus: Cultivate for 2 days at a temperature of 30°C and a pH of 5.5, and the bacterial liquid concentration is (8 - 10)×10 7 CFU / mL.

[0041] Example 2

[0042] A method for treating coal slime water includes the following steps:

[0043] Step 1: Drain the coal slime water into the primary sedimentation tank and let it settle naturally for 8 hours. Then drain the coal slime water after primary sedimentation treatment into the regulation tank. The coal slime particles settled at the bottom of the primary sedimentation tank are collected and subjected to pressure filtration. The sewage obtained from pressure filtration is continuously drained back into the primary sedimentation tank and then subjected to treatments such as regulation and filtration. Before the primary sedimentation coal slime water is drained into the regulation tank, it also includes flotation treatment;

[0044] Step 2: Add the first microbial flocculant into the regulation tank, stir and adjust the pH of the coal slime water to 8.0. The coal slime water undergoes flocculation sedimentation to obtain the secondary sedimentation coal slime water;

[0045] Step 3: Add the second microbial flocculant into the secondary sedimentation coal slime water. The coal slime water undergoes flocculation sedimentation again to obtain the tertiary sedimentation coal slime water, which is filtered by a filtration device and then drained into the clear water tank. The settled coal slime particles are respectively collected and subjected to pressure filtration. The sewage obtained from pressure filtration is continuously drained back into the regulation tank and then subjected to treatments such as filtration;

[0046] Among them, the volume ratio of the first microbial flocculant to the coal slime water is 20:100. The first microbial flocculant is the fermentation extract of Bacillus subtilis and yeast extract, and the mass ratio of the two is 2:1. The second microbial flocculant is Aspergillus fumigatus, and the volume ratio to the coal slime water is 15:100. A coagulant aid is added before adding the first microbial flocculant into the regulation tank. The coagulant aid is an aqueous solution of bone glue and sodium alginate with a mass fraction of 2.5%. The mass ratio of bone glue to sodium alginate is 1:30, and the mass ratio of the coagulant aid to the coal slime water is 1:70.

[0047] Among them, the fermentation extract of Bacillus subtilis: Inoculate the Bacillus subtilis seed culture solution into the culture medium, and carry out aerobic fermentation for 2 - 4 days under the conditions of a temperature of 32°C and a rotation speed of 240 revolutions per minute. Filter the obtained fermentation broth, and evaporate and concentrate the filtrate to obtain the fermentation extract of Bacillus subtilis.

[0048] Among them, the cultivation of Aspergillus fumigatus: Cultivate for 7 days under the conditions of a temperature of 32°C and a pH of 7.5, and the bacterial liquid concentration is (8 - 10)×10 7 cells / mL.

[0049] Example 3

[0050] A method for treating coal slime water, comprising the following steps:

[0051] Step 1: Drain the coal slime water into the primary sedimentation tank and let it settle naturally for 7 hours. Then drain the coal slime water after primary sedimentation treatment into the regulation tank. The coal slime particles settled at the bottom of the primary sedimentation tank are collected and subjected to pressure filtration. The sewage obtained from pressure filtration is continuously drained back into the primary sedimentation tank and then subjected to treatments such as regulation and filtration. Before the primary sedimentation coal slime water is drained into the regulation tank, it also includes flotation treatment;

[0052] Step 2: Add the first microbial flocculant into the regulating tank, stir and adjust the pH of the slime water to 7.0, and let the slime water undergo flocculation sedimentation to obtain the secondary sedimented slime water;

[0053] Step 3: Add the second microbial flocculant into the secondary sedimented slime water, let the slime water undergo flocculation sedimentation again, and the tertiary sedimented slime water is filtered by a filtering device and then discharged into the clear water tank; the sedimented coal slime particles are collected separately and then subjected to pressure filtration treatment, and the sewage obtained by pressure filtration is continuously discharged into the regulating tank and then subjected to filtration and other treatments;

[0054] Among them, the volume ratio of the first microbial flocculant to the slime water is 12:100. The first microbial flocculant is the fermentation extract of Bacillus subtilis and yeast extract, and the mass ratio of the two is 2:0.8; the second microbial flocculant is Aspergillus fumigatus, and the volume ratio to the slime water is 9:100; a coagulant aid is added before adding the first microbial flocculant into the regulating tank. The coagulant aid is an aqueous solution of bone glue and sodium alginate with a mass fraction of 2.0%, and the mass ratio of bone glue to sodium alginate is 1:20. The mass ratio of the coagulant aid to the slime water is 1:60.

[0055] Among them, inoculate the Bacillus subtilis seed culture solution into the culture medium, and carry out aerobic fermentation for 2-4 days under the conditions of a temperature of 31°C and a rotation speed of 170 revolutions per minute, filter the obtained fermentation broth, and evaporate and concentrate the filtrate to obtain the fermentation extract of Bacillus subtilis.

[0056] Among them, the cultivation of Aspergillus fumigatus: cultivate for 5 days under the conditions of a temperature of 31°C and a pH of 6.5, and the bacterial liquid concentration is (8-10)×10 7 cells / mL.

[0057] Comparative Example 1

[0058] The difference between Comparative Example 1 and Example 1 is that: the second microbial flocculant is not added.

[0059] Comparative Example 2

[0060] The difference between Comparative Example 2 and Example 1 is that: the coagulant aid is not added.

[0061] Use the formula: flocculation rate = (Ao - Ai)÷Ao×100% to calculate the flocculation rates in Examples 1 to 3 and Comparative Examples 1 to 2, and the results are shown in Table 1. In the formula, Ao is the OD660nm value of the supernatant of the slime water without any treatment, and Ai is the OD660nm value of the supernatant of each finally sedimented slime water; the OD value is measured at 660nm by a UV-5100 ultraviolet-visible spectrophotometer.

[0062] Table 1

[0063]

[0064]

[0065] As can be seen from the above, compared with the comparative examples, in each embodiment of the present invention, a first microbial flocculant is added to the slime water after short-term natural sedimentation. The yeast extract and Bacillus subtilis fermentation extract in it contain a large amount of components such as proteins and polysaccharides, and have good flocculation effects on fine particulate matter and clay minerals in the slime water. And a second microbial flocculant containing Aspergillus fumigatus is added to enhance its flocculation and sedimentation effect on fine particulate matter, further improving the flocculation effect of the slime water, enabling the combustibles in the slime water to be fully recycled and greatly shortening the sedimentation time.

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for treating coal slime water, characterized in that, The slime water contains fine particulate matter and clay minerals, and the treatment method includes the following steps: Step S1, naturally sediment the slime water for 6 - 8 h to obtain primary sedimented slime water; Step S2, add a coagulant aid solution to the primary sedimented slime water, then add a first microbial flocculant, and adjust the pH of the primary sedimented slime water to 6.0 - 8.0 to obtain secondary sedimented slime water; Step S3, add a second microbial flocculant to the secondary sedimented slime water to obtain tertiary sedimented slime water, and filter and discharge it into a clear water tank; Among them, the mass fraction of the coagulant aid in the coagulant aid solution is 1.5 - 2.5%, the coagulant aid includes bone glue and sodium alginate, and the mass ratio of the bone glue to the sodium alginate is 1:(10 - 30); the volume ratio of the coagulant aid solution to the primary sedimented slime water is 1:(50 - 70); The first microbial flocculant includes a fermentation extract of Bacillus subtilis and yeast extract. In the first microbial flocculant, the mass ratio of the fermentation extract of Bacillus subtilis to the yeast extract is 2:(0.5 - 1); the volume ratio of the first microbial flocculant to the primary sedimented slime water is (2 - 20):100; The second microbial flocculant includes Aspergillus fumigatus, and the volume ratio of the second microbial flocculant to the secondary sedimented slime water is (3 - 15):

100.

2. The processing method according to claim 1, characterized in that The fermentation extract of Bacillus subtilis is obtained by the following method: inoculate the Bacillus subtilis seed culture solution in a medium, perform aerobic fermentation to obtain a fermentation broth; filter the fermentation broth, and evaporate and concentrate the filtrate to obtain the fermentation extract of Bacillus subtilis.

3. The processing method according to claim 2, characterized in that, The temperature of the aerobic fermentation is 30 - 32 °C, the rotation speed is 120 - 240 rpm, and the time is 2 - 4 days.

4. The processing method according to claim 1 or 2, characterized in that, The culture conditions of the Aspergillus fumigatus include: temperature is 30~32°C, pH is 5.5~7.5, time is 2~7 days, and the concentration of the bacterial solution is (8~10)×10 7 CFU / mL.

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