A method for enriching and separating arsenic, a harmful component, from drilling waste mud.

Abstract

This invention relates to a method for enriching and separating arsenic, a harmful component, from drilling waste mud. The method includes the following steps: 1) treating iron powder with an acid solution and drying it to obtain an enriching agent; 2) thoroughly mixing the arsenic-containing waste mud with an intensifier and the prepared enriching agent to react, causing arsenic to accumulate on the surface of the enriching agent; 3) separating the reacted enriching agent from the waste mud using a strong magnetic field to obtain a small amount of waste residue and arsenic-removed mud. The arsenic content in the waste mud treated by this invention is reduced. The treated waste mud can be used as roadbed filler or for brick making, cement making, etc., avoiding secondary pollution that may occur with conventional stabilization. This invention does not generate wastewater during the treatment process. The reagents used in this invention are low-cost, the process is simple, and the effect is good. The amount of waste residue collected by this invention is small, and the arsenic in the waste residue is passivated, allowing for resource utilization or landfill.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste mud treatment, and more particularly, to a method for enriching and separating harmful components of arsenic in drilling waste mud. BACKGROUND

[0002] Waste drilling mud is one of the main pollutants in the oil industry. It contains clay, weighting material, various chemical treatment agents, sewage, waste oil and drill cuttings, etc. It is a multiphase stable colloidal system. In recent years, the government has increased its efforts to manage waste mud generated during land oil and gas exploration. Non-landing treatment technology and resource utilization technology have been well developed. For example, CN106194078B discloses a drilling mud non-landing treatment device. After lifting, oil removal, water replenishment, destabilization and rock separation, the mud and water are reused; CN201777969U discloses a harmless treatment device for waste drilling mud. After pretreatment, mud-water separation, sewage treatment and deep filtration, the water meets the reuse or discharge standard; CN111520090A discloses a method for breaking and improving natural gas drilling waste, and the solid waste obtained by pressure filtration can be used as a roadbed filler; CN112225589A discloses a method for preparing humus soil by mixing drilling waste mud cake with cow dung, straw and biological bacteria; CN105198385A discloses a method for preparing environment-friendly ceramic filter material by mixing oilfield waste drilling mud with mud, waste glass powder and tailings sand, etc. through processes such as batching, balling, drying and sintering; CN110255934A discloses a method for producing oil well cement using oil-based drilling mud cuttings. After mud-water separation, the mud cake needs to be considered for harmful components, and the harmful components in the mud cake need to be removed or harmlessly treated before being used for road paving, composting, cement preparation or other purposes. Analysis shows that some drilling waste mud contains heavy metal components such as arsenic, copper, nickel, lead and cadmium, and arsenic is over standard. If these harmful components, especially arsenic, are not separated and harmlessly treated, secondary pollution may occur.

[0003] Currently, the main methods for treating arsenic-contaminated soil are plant remediation, microbial remediation, electrokinetic remediation, leaching remediation and passivation remediation. Among these methods, the passivation method has the characteristics of easy operation, short cycle and good effect, and has been widely used. However, drilling mud is different from conventional soil, and the remediation method for contaminated soil cannot be directly used for harmless treatment of drilling mud. Therefore, it is urgent to find a simple, efficient and low-cost method for separating or harmlessly treating arsenic and other contaminated components in drilling mud, which is a prerequisite for harmless and resourceful treatment of drilling waste mud contaminated by arsenic and other heavy metals, and has important significance for promoting the green and circular development of oilfields and building green oilfields.

[0004] Therefore, it is desirable to design a method for enriching and separating harmful component arsenic in drilling waste mud. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for enriching and separating harmful component arsenic in drilling waste mud, the harmful component arsenic content in the treated waste mud is reduced, and the waste mud can be further resource utilization.

[0006] In order to solve the above technical problems, the present application adopts the following technical solutions:

[0007] The principle of the present application is described as follows: (1) iron powder reacts with acid (excess iron), which corrodes the surface of the iron powder, increases the surface area, and forms ferrite at the same time; (2) alkaline conditions promote the free precipitation of arsenic, and form iron arsenic compounds with iron ions near the surface of the iron powder, which are solidified; (3) the solidified arsenic and iron are separated in the magnetic separation process.

[0008] Specifically:

[0009] According to an aspect of the present application, a method for enriching and separating harmful component arsenic in drilling waste mud is provided, comprising the following steps:

[0010] 1) treating the iron powder with an acid solution and drying to obtain an enrichment agent;

[0011] 2) mixing the arsenic-containing waste mud with the reinforcing agent and the prepared enrichment agent to react, so that the arsenic is enriched on the surface of the enrichment agent;

[0012] 3) separating the enrichment agent after mixing and reaction from the waste mud by strong magnetism to obtain a small amount of waste residue and dearsenized mud.

[0013] In an embodiment of the present application, the particle size of the iron powder in step 1) is 50-200 mesh.

[0014] In an embodiment of the present application, the concentration of the acid solution in step 1) is 0.01-1 mol / L, and the amount of the acid solution is calculated according to the molar ratio of hydrogen ion to iron being less than 0.5.

[0015] In an embodiment of the present application, the acid solution is an organic acid solution.

[0016] In an embodiment of the present application, the organic acid solution is oxalic acid solution or citric acid solution.

[0017] In an embodiment of the present application, the acid solution is an inorganic acid solution.

[0018] In an embodiment of the present application, the inorganic acid solution is hydrochloric acid solution or phosphoric acid solution.

[0019] In one embodiment of the present application, the amount of the enrichment agent added in step 2) is 2-20 g of the enrichment agent per 1 kg of the waste mud.

[0020] In one embodiment of the present application, the strengthening agent in step 2) is an alkali solution.

[0021] In one embodiment of the present application, the alkali solution is a 0.1 mol / L sodium hydroxide solution.

[0022] In one embodiment of the present application, the amount of the sodium hydroxide solution added is 20-100 mL of the sodium hydroxide solution per 1 kg of the waste mud.

[0023] In one embodiment of the present application, the water content of the waste mud in step 2) is 20%-21%.

[0024] In one embodiment of the present application, the reaction time in step 2) is 3-10 days.

[0025] In one embodiment of the present application, the small amount of the waste residue in step 3) is the enrichment agent and the mud attached to the enrichment agent.

[0026] In one embodiment of the present application, the mud attached to the enrichment agent is 1%-5% of the initial waste mud.

[0027] By using the above technical solution, the present application has the following advantages compared with the prior art:

[0028] The content of the pollutant arsenic in the treated waste mud is reduced, the treated waste mud can be used as a roadbed filler or for making bricks, making cement and the like, and the secondary pollution possibly caused by the conventional stabilization is avoided; the present application does not produce sewage in the treatment process; the reagent used in the present application has low cost, the process is simple, and the effect is good; the amount of the waste residue collected in the present application is small, and the arsenic in the waste residue is in a passivated state, which can be resourceized or landfilled. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A process diagram of a method for enriching and separating harmful components arsenic in waste drilling mud provided by the present application is shown. DETAILED DESCRIPTION

[0030] It should be understood that the embodiments of the present application shown in the example embodiments are only illustrative. Although only a few embodiments are described in detail in the present application, those skilled in the art can easily appreciate that various modifications are possible without departing from the teachings of the present application subject matter. Accordingly, all such modifications should be included in the scope of the present application. Other substitutions, modifications, changes and omissions can be made to the design, operating conditions and parameters of the following example embodiments without departing from the spirit of the present application.

[0031] like Figure 1 As shown, a method for enriching and separating arsenic, a harmful component, from drilling waste mud includes the following steps:

[0032] Iron powder is treated with an acid solution and then dried to obtain an enriching agent;

[0033] Arsenic-containing waste mud is thoroughly mixed with a strengthening agent and a prepared enriching agent to react, so that arsenic is enriched on the surface of the enriching agent.

[0034] The enriching agent after the mixed reaction is separated from the waste mud by strong magnetic field, resulting in a small amount of waste residue and arsenic removal mud.

[0035] Through the above method, the arsenic content of pollutants in the waste mud treated by the present invention is reduced. The treated waste mud can be used as roadbed filler or for brick making, cement making, and other purposes, avoiding secondary pollution that may be caused by conventional stabilization. The treatment process of the present invention does not generate wastewater. The reagents used in the present invention are low in cost, the process is simple, and the effect is good. The amount of waste residue collected by the present invention is small, and the arsenic in the waste residue is passivated and can be used for resource utilization or landfill.

[0036] In the above method, the particle size of the iron powder is 50-200 mesh, preferably 50-100 mesh.

[0037] In the above method, the concentration of the acid solution is 0.01-1 mol / L, preferably 0.2 mol / L; the amount of acid solution used is calculated based on a molar ratio of hydrogen ions to iron of less than 0.5, preferably less than 0.2.

[0038] In the above method, the acid solution is an organic acid solution.

[0039] In the above method, the organic acid solution is either oxalic acid solution or citric acid solution.

[0040] In the above method, the acid solution can also be an inorganic acid solution.

[0041] In the above method, the inorganic acid solution is either hydrochloric acid solution or phosphoric acid solution.

[0042] In the above method, the amount of enriching agent added in the mixed reaction is 2-20g of enriching agent per 1kg of waste mud.

[0043] In the above method, the reinforcing agent is an alkaline solution.

[0044] In the above method, the alkaline solution is a 0.1 mol / L sodium hydroxide solution.

[0045] In the above method, the amount of sodium hydroxide solution added is 20-100 mL of sodium hydroxide solution per 1 kg of waste mud.

[0046] In the above method, the moisture content of the waste mud is 20%-21%.

[0047] In the above method, the mixing reaction time is 3-10 days.

[0048] In the above method, a small amount of waste residue consists of enriching agent and mud adhering to the enriching agent.

[0049] In the above method, the slurry adhering to the enriching agent is 1%-5% of the initial waste slurry.

[0050] The technical solutions of the present invention will be described in detail below through specific embodiments.

[0051] A sample of drilling mud cake contaminated with arsenic, containing 21% water, was taken. After drying, the arsenic content in the sample was determined using the atomic fluorescence spectrometry method (GBT22105.2-2008) specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content was found to be 60.1 mg / kg (60.1 mg of arsenic per kg of mud cake sample). The mud cake sample containing arsenic was then pulverized for later use.

[0052] Comparative Example 1

[0053] Weigh 50g of the above-mentioned mud cake sample (containing approximately 10g of water), add 0.5g of reduced iron powder with a particle size between 50-100 mesh as a enriching agent, stir and mix thoroughly, and maintain for 7 days. Afterwards, the mixture is separated using a strong magnetic field, yielding approximately 0.8g of waste residue (enriching agent and attached mud cake). After drying, the separated mud cake sample is analyzed using the "Determination of Total Mercury, Total Arsenic, and Total Lead in Soil Quality—Part 2—Atomic Fluorescence Method" (GBT22105.2-2008) as specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content was found to be 58.7mg / kg, resulting in an arsenic removal rate of 2.3%.

[0054] Example 1

[0055] Preparation of enriching agent: Immerse 10g of reduced iron powder with a particle size between 50-100 mesh in 10mL of 0.2mol / L oxalic acid solution, keep for 10 minutes, filter out the aqueous solution and air dry to obtain the enriching agent.

[0056] Weigh 50g of the above-mentioned mud cake sample (containing approximately 10g of water), add 0.5g of the enriching agent prepared according to the above method, stir and mix thoroughly, and maintain for 7 days. Afterwards, the mixture is separated using strong magnetic separation to obtain approximately 1.0g of waste residue (enriching agent and attached mud cake). The separated mud cake sample is dried and then the arsenic content in the sample is determined using the atomic fluorescence spectrometry method (GBT22105.2-2008) specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content is found to be 53.2mg / kg, thus the arsenic removal rate is calculated to be 11.5%.

[0057] Example 2

[0058] The method for preparing the enriching agent is the same as in Example 1.

[0059] Weigh 50g of the above-mentioned mud cake sample (containing approximately 10g of water), add 0.5g of the enriching agent prepared above, and add 5mL of 0.1mol / L NaOH solution. Stir and mix thoroughly, keeping the sample moist for 7 days. Afterward, the mixture is separated using strong magnetic separation, yielding approximately 1.4g of waste residue (enriching agent and attached mud cake). The separated mud cake sample is dried and then analyzed for arsenic content using the atomic fluorescence spectrometry method (GBT22105.2-2008) specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content was found to be 33.4mg / kg, resulting in an arsenic removal rate of 44.4%.

[0060] Example 3

[0061] The method for preparing the enriching agent is the same as in Example 1.

[0062] Weigh 50g of the above-mentioned mud cake sample (containing approximately 10g of water), add 0.3g of the enriching agent prepared above, and add 5mL of 0.1mol / L NaOH solution. Stir and mix thoroughly, keeping the sample moist for 5 days. Afterward, the mixture is separated using strong magnetic separation, yielding approximately 1.2g of waste residue (enriching agent and attached mud cake). The separated mud cake sample is dried and then analyzed for arsenic content using the atomic fluorescence spectrometry method (GBT22105.2-2008) specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content was found to be 35.7mg / kg, resulting in an arsenic removal rate of 40.6%.

[0063] Example 4

[0064] Preparation of enriching agent: Immerse 10g of reduced iron powder with a particle size between 50-100 mesh in 10mL of 0.2mol / L hydrochloric acid solution, keep for 10 minutes, filter out the aqueous solution and air dry to obtain the enriching agent.

[0065] Weigh 50g of the above-mentioned mud cake sample (containing approximately 10g of water), add 0.3g of the enriching agent prepared according to the above method, and add 5mL of 0.1mol / L NaOH solution. Stir and mix thoroughly, keeping the sample moist for 5 days. Afterward, the mixture is separated using strong magnetic separation, yielding approximately 1.0g of waste residue (enriching agent and attached mud cake). After drying, the separated mud cake sample is analyzed using the "Determination of Total Mercury, Total Arsenic, and Total Lead in Soil Quality—Part 2—Atomic Fluorescence Method" (GBT22105.2-2008) as specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content was found to be 47.8mg / kg, resulting in an arsenic removal rate of 20.5%.

[0066] Example 5

[0067] Preparation of enriching agent: Immerse 10g of reduced iron powder with a particle size between 50-100 mesh in 10mL of 0.2mol / L citric acid solution, keep for 10 minutes, filter out the aqueous solution and air dry to obtain the enriching agent.

[0068] Weigh 50g of the above-mentioned mud cake sample (containing approximately 10g of water), add 0.3g of the enriching agent prepared according to the above method, add 5mL of 0.1mol / L NaOH solution, stir and mix thoroughly, keeping the sample moist for 5 days. Afterwards, the mixture is separated using strong magnetic separation, yielding approximately 1.0g of waste residue (enriching agent and attached mud cake). The separated mud cake sample is dried and then analyzed for arsenic content using the atomic fluorescence spectrometry method (GBT22105.2-2008) specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content was found to be 46.3mg / kg, resulting in an arsenic removal rate of 23.0%.

[0069] Example 6

[0070] Preparation of enriching agent: Immerse 10g of reduced iron powder with a particle size between 50-100 mesh in 10mL of 0.2mol / L phosphoric acid solution, keep for 10 minutes, filter out the aqueous solution and air dry to obtain the enriching agent.

[0071] Weigh 50g of the above-mentioned mud cake sample (containing approximately 10g of water), add 0.3g of the enriching agent prepared according to the above method, add 5mL of 0.1mol / L NaOH solution, stir and mix thoroughly, keeping the sample moist for 5 days. Afterwards, the mixture is separated using strong magnetic separation, yielding approximately 1.2g of waste residue (enriching agent and attached mud cake). After drying, the separated mud cake sample is analyzed using the "Determination of Total Mercury, Total Arsenic, and Total Lead in Soil Quality—Part 2—Atomic Fluorescence Method" (GBT22105.2-2008) as specified in the "Soil Environmental Quality Standard for Construction Land Soil Pollution Risk Control (Trial)" (GB 36600-2018). The total arsenic content is found to be 35.2mg / kg, resulting in an arsenic removal rate of 41.4%.

[0072] As can be seen from the results of Comparative Example 1 and Examples 1-6 above, the arsenic content of pollutants in the waste mud treated by the present invention is reduced. The treated waste mud can be used as roadbed filler or for brick making, cement making, etc., avoiding secondary pollution that may be caused by conventional stabilization. The amount of waste residue collected by the present invention is small, and the arsenic in the waste residue is passivated by treatment, which can be used for resource utilization or landfill.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for the enrichment and separation of the harmful component arsenic in drilling waste mud, characterized in that The method comprises the following steps: 1) treating excess iron powder with an acid solution and drying to obtain an enrichment agent, wherein the concentration of the acid solution is 0.01-1 mol / L, and the amount of the acid solution is calculated according to a molar ratio of hydrogen ions to iron less than 0.5; 2) mixing and reacting the waste mud containing arsenic with the reinforcing agent and the obtained enrichment agent to enrich arsenic on the surface of the enrichment agent; 3) separating the mixed and reacted enrichment agent and waste mud by strong magnetism to obtain a small amount of waste residue and arsenic-removed mud.

2. The method of the enrichment and separation of harmful components arsenic in drilling waste mud according to claim 1, characterized in that, The particle size of the iron powder in the step 1) is 50-200 mesh.

3. The method of the enrichment and separation of harmful components arsenic in drilling waste mud according to claim 1, characterized in that, The acid solution is an organic acid solution.

4. The method of claim 3, wherein the method is characterized by, The organic acid solution is oxalic acid solution or citric acid solution.

5. The method of the enrichment and separation of harmful components arsenic in drilling waste slurry according to claim 1, characterized in that, The acid solution is an inorganic acid solution.

6. The method of concentrating and separating arsenic, a harmful component of drilling waste mud according to claim 5, characterized by, The inorganic acid solution is hydrochloric acid solution or phosphoric acid solution.

7. The method of the enrichment and separation of harmful components arsenic in drilling waste mud according to claim 1, characterized in that, The amount of the enrichment agent added in the step 2) is 2-20 g per 1 kg of waste mud.

8. The method of concentrating and separating arsenic, a harmful component of drilling waste mud according to claim 1, characterized by, The reinforcing agent in the step 2) is an alkali solution.

9. The method of the enrichment and separation of harmful components arsenic from drilling waste slurry according to claim 8, characterized in that, The alkali solution is 0.1 mol / L sodium hydroxide solution.

10. The method of the enrichment and separation of harmful components arsenic in drilling waste mud according to claim 9, characterized in that, The amount of the sodium hydroxide solution added is 20-100 mL per 1 kg of waste mud.

11. The method of concentrating and separating arsenic, a harmful component of drilling waste mud according to claim 1, characterized by, The water content of the waste mud in the step 2) is 20%-21%.

12. The method of concentrating and separating arsenic, a harmful component of drilling waste mud according to claim 1, characterized by, The reaction time in the step 2) is 3-10 days.

13. The method of concentrating and separating arsenic, a harmful component of drilling waste mud according to claim 1, characterized by, The small amount of waste residue obtained in the step 3) is the enrichment agent and the mud attached to the enrichment agent.

14. The method of concentrating and separating arsenic, a harmful component of drilling waste mud according to claim 13, characterized by, The mud attached to the enrichment agent is 1%-5% of the initial waste mud.

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