A method for harmless treatment of oily waste clay

Abstract

This invention belongs to the solid waste disposal industry, specifically a method for the harmless treatment of oily waste bleaching clay. A washing agent and water are added to the oily waste bleaching clay to be treated. Under hydrophilic and oleophilic equilibrium conditions, the clay is washed thoroughly 1-3 times. After washing, the liquids from multiple washes are combined and treated with a demulsifier to form an oil-in-water flotation, thus completing the three-phase separation of oil, agent, and water. The solid matter remaining after washing is the harmless bleaching clay. This invention exhibits a high removal rate for bleaching clay with a petroleum hydrocarbon content ranging from 5% to 30% when extruded into granules or powder. This harmless treatment technology has a certain degree of adaptability; the process is simple, operation and management are convenient, crude oil recovery and treated bleaching clay consistently meet standards, and the overall cost is relatively low. The technical system constructed by this invention provides technical support for the "harmless and resource-based" treatment of solid waste in my country's waste bleaching clay sector.

Description

Technical Field

[0001] This invention belongs to the solid waste disposal industry, specifically a method for the harmless treatment of oily waste clay. Background Technology

[0002] Activated clay is widely used in the refining process of products such as lubricating oil and paraffin wax. In the process of refining petrochemical products such as lubricating oil and paraffin wax, activated clay achieves the refining effect by adsorbing a certain amount of impurities. As the amount of adsorption increases, the clay becomes saturated and turns into waste clay containing oil or wax.

[0003] After treatment, the main pollutant in bleached clay is petroleum hydrocarbons. With the rapid development of the petrochemical industry, the output of waste bleached clay is increasing annually, making its treatment and the recovery of lubricating oil or paraffin wax a major industry challenge. The main disposal methods for waste bleached clay include landfill, incineration, biological treatment, solvent cleaning, and water washing. Landfilling, however, requires a large land area, pollutes the environment, and endangers groundwater quality. When the oil in the waste bleached clay is highly unsaturated, it is prone to spontaneous combustion upon contact with air, posing a fire risk. Incineration is a comprehensive process of high-temperature decomposition and deep oxidation. Bleached clay treatment companies can oxidize and decompose oily waste bleached clay through incineration, achieving the technical effects of reducing volume, removing toxicity, and recovering energy. However, the incineration of waste bleached clay produces some acidic gases, unburned organic components, and slag, which may lead to secondary pollution. To reduce pollution, the incineration process must be equipped with pollution control facilities and precise online monitoring, resulting in high construction investment and operation and management costs, thus increasing the overall treatment cost.

[0004] Although biological methods are less expensive, they are more time-consuming and less effective than other methods, and the resulting bacterial residue is not easy to dispose of quickly.

[0005] Solvent cleaning methods typically use solvents such as sulfolane, benzene, and gasoline to circulate and clean pretreated oily clay or sludge. This method is widely used in the bulk organic chemical and petrochemical industries, but the construction costs required are higher than those of other treatment methods of the same scale.

[0006] The water washing method has been studied to some extent by scholars and engineers both domestically and internationally, including the optimization of cleaning agent formulations and cleaning process operations. If the bleached clay treated with water is identified as non-hazardous waste after hazardous waste identification, it can be treated as general solid waste or applied for point-to-point resource utilization. However, in actual pilot-scale and engineering operations, there are technical problems such as a heavy burden of wastewater treatment and unsatisfactory and unstable cleaning agent effects.

[0007] Therefore, research on the water washing treatment of waste bleaching clay has high practical significance.

[0008] This invention proposes a highly feasible treatment method for this type of oily solid waste. Summary of the Invention

[0009] The purpose of this invention is to provide a method for the harmless treatment of oily waste clay.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A method for harmlessly treating oily waste bleaching clay involves adding a detergent and water to the oily waste bleaching clay to be treated, washing it thoroughly 1-3 times under hydrophilic and oleophilic equilibrium conditions, separating the washed products, and combining the water emulsions from multiple washes with a demulsifier to form an oil-in-water flotation, thereby completing the three-phase separation of oil, detergent, and water; the solid material after washing is the harmless bleaching clay.

[0012] When the oil content in the oily waste clay to be treated is greater than 25%, the oily waste clay to be treated is mixed with water, and then pre-washed with a 0.1 wt% crown ether aqueous solution for later use; wherein, the mass ratio of clay to water is 1:5-20.

[0013] Detergent and water are added to the oily waste clay to be treated. The detergent spreads and wets the solid surface, gradually displacing the oil. The oil, initially spread evenly on the solid surface, gradually curls into oil droplets, increasing the contact angle and changing from wetting to non-wetting. Under mechanical action, the "curled" oil droplets detach from the surface and enter the aqueous solution, where they are emulsified by surfactants and stably dispersed in the washing liquid. As the wetted and emulsified oil enters the surfactant micelles in the detergent, it no longer deposits on the surface of the bleached clay being cleaned. Heating to 60-80℃ causes the detergent in the system to produce a cloud point effect, accelerating the wetting and emulsification of the oil in the bleached clay into the washing liquid. The system is thoroughly washed 1-3 times. After washing, the bleached clay is collected, filtered using a plate filter, and air-dried to obtain harmless bleached clay for safe disposal and utilization.

[0014] The process involves adding detergent and water to the oily waste bleaching clay to be treated, mixing and stirring until homogeneous, and ensuring an HLB value within the range of 13-15 under balanced hydrophilic and oleophilic conditions. The mixture is then heated to below the cloud point (60-80℃), and stirred for 30-60 minutes for washing. This washing is repeated 1-2 times. After washing, the bleaching clay is collected, filtered using a plate filter, and air-dried to obtain harmless bleaching clay for safe discharge. The mass ratio of detergent, bleaching clay, and water is 1:10:30 to 1:10:200.

[0015] The detergent is one or more of the following: fatty alcohol polyoxyethylene ether AEO-7, fatty alcohol polyoxyethylene ether AEO-9, nonylphenol polyoxyethylene ether NP-9, nonylphenol polyoxyethylene ether NP-10, nonylphenol polyoxyethylene ether NP-15, sodium dodecylbenzenesulfonate, and lauryl alcohol polyoxyethylene ether. Preferably, it is a mixture of any two or three of the above detergents, and the proportions are adjusted according to the oil content and type in the sample to be treated.

[0016] The washing wastewater after washing is combined, and a demulsifier is added to form a mixed layer of oil and detergent on the upper part of the washing water. The oil layer is collected after separation, and then solvent A is added to the oil layer to separate the detergent from the oil. The resulting detergent is reused, and the separated oil is collected and reused.

[0017] The amount of demulsifier added is 5-15% of the weight of the washing wastewater to be demulsified.

[0018] The demulsifier is a mixture of 1% by weight of a 0.1% crown ether aqueous solution, 15-60% anhydrous sodium sulfate, and the remainder being sodium chloride; after mixing, it is added and stirred under heating conditions to 35-55°C to form a demulsified state; the solvent A is one or more of ethanol, acetonitrile, and methanol.

[0019] The 0.1% crown ether aqueous solution used in the pre-cleaning process and the 0.1% crown ether aqueous solution used in the demulsifier are both aqueous solutions of 15-crown ether-5 with a concentration of 0.1 wt%. The amount of effective crown ether added during pre-cleaning is guaranteed to be one part per ten thousand to one part per ten thousand of the water mass.

[0020] The water after demulsification is evaporated and recovered by an evaporation device, and can be reused for further washing of the oily waste clay to be treated.

[0021] Advantages of this invention:

[0022] This invention first employs a hot washing method to clean oil-containing bleaching clay. Utilizing the cloud point effect, it enhances the wetting, emulsifying, and solubilizing abilities of the detergent, causing the oil to desorb from the surface and pores of the waste bleaching clay and enter the aqueous phase. After washing, the bleaching clay is rendered harmless. Then, a surfactant demulsification effect is used to recover the oil-containing wastewater from the cleaned waste bleaching clay, forming an oil-in-water flotation. This completes the three-phase separation of oil, detergent, and water. Specifically:

[0023] (1) The crude oil recovered and the treated silt obtained by the method of this invention meet the national standard GB5085.6, which specifies that the petroleum hydrocarbon content is <3%. The system is controlled by a combination of automatic and manual operation. The waste is identified as non-hazardous waste and can be further utilized for resource recovery.

[0024] (2) The white clay treated by the present invention can be used as asphalt material for road paving after being reprocessed with the waste residue generated in the flocculation process, which can generate good economic benefits and reduce secondary pollution.

[0025] (3) Low equipment investment and suitable for small-scale processing.

[0026] (4) The process is simple, the operation and management are convenient, and the daily operating costs are low. Detailed Implementation

[0027] The following examples further illustrate specific embodiments of the present invention. It should be noted that the specific embodiments described herein are merely for illustration and explanation and are not intended to limit the scope of the present invention.

[0028] This invention demonstrates a high removal rate for bleaching clay with a petroleum hydrocarbon content ranging from 5% to 30% when extruded into granules or powder. This harmless treatment technology exhibits considerable adaptability; the process is simple, operation and management are convenient, and the recovered crude oil and treated bleaching clay consistently meet standards, with relatively low overall costs. The technical system developed in this invention provides technical support for the "harmless and resource-based" treatment of solid waste in my country's bleaching clay sector.

[0029] Example 1: Case Study of Harmless Treatment of White Soil

[0030] Target oily clay: A clay disposal company collects oily clay from petrochemical enterprises. After processing with lime extrusion, the oil content is 12-21%. The main impurity is lubricating oil. It appears as a brown granular solid with a strong oily smell.

[0031] The above-mentioned oily clay to be treated was divided into 10 parts, and then divided into two batches. Each batch consisted of 5 parallel batches. One batch (S1-S5) was treated using the method of the present invention to render the clay harmless. The other batch (S1-S5) was treated using the washing agent formula 1 of step 1 of the following harmless treatment process, which consisted of potassium tripolyphosphate, sodium dodecylbenzenesulfonate, and fatty alcohol polyoxyethylene ether AEO-10 ​​in a mass ratio of 3:6:1. At the same time, the mass ratio of washing agent, clay, and water was 1:10:50.

[0032] Harmless treatment process:

[0033] 1) Add the extruded waste bleaching clay to the "washing tank," along with industrial water and a washing agent (mass ratio of nonylphenol polyoxyethylene ether NP-9: lauryl alcohol polyoxyethylene ether: sodium dodecylbenzenesulfonate = 15:4:1). Stir and heat to 70°C, and continue stirring for 40 minutes. Homogenize the washing agent, water, and oily bleaching clay, then wash the clay. After washing, drain the washing water and wash again using the same method. After two washings, filter the bleaching clay and air dry. The mass ratio of washing agent, bleaching clay, and water is 1:10:50.

[0034] 2) Combine the above-mentioned washing wastewater and add it to a separation tank. Then, add 10% (by weight of total washing wastewater) of demulsifier (1% of a 0.1 wt% crown ether aqueous solution (0.1% of a 15-crown ether-5 aqueous solution), 39% sodium chloride, and 60% sodium sulfate to the separation tank. Heat to 50 degrees Celsius and stir to form a mixture of oil and detergent. Use an oil separator to remove the upper oil layer. Then, add 10% (by weight of oil layer) of industrial ethanol to the remaining system to extract the detergent from the oil layer and dissolve it in an ethanol aqueous solution for reuse. The detergent is then collected in a washing liquid tank for use in the next washing mixture, thereby reducing operating costs.

[0035] 3) After separation, the crude oil is mixed with other crude oils in a crude oil tank, and after water removal, it is sent out. The wastewater solution after separation is treated in an oil-water separator and then recycled to reduce operating costs.

[0036] The content of petroleum hydrocarbons in the washed silt was determined by infrared spectroscopy according to Appendix 0 of GB 5085.6, which specifies the determination of the total amount of recyclable petroleum hydrocarbons in solid waste (see Table 1). The data shows that the removal rate of petroleum hydrocarbons by the formula of this invention is higher than that of typical bleaching clay cleaning formula 1. The material treated by the method of this invention can be stacked and applied to the building materials industry.

[0037] Table 1 Comparison results with other typical cleaning agent formulations

[0038]

[0039] Example 2

[0040] Target oily clay: A clay disposal company collects oily clay from petrochemical enterprises. After processing using the lime extrusion method, the oil content is approximately 25-30%. The main components are lubricating oil and light oil. It appears as dark gray solid granules with a strong oily and pungent odor (see Table 2).

[0041] Table 2

[0042]

[0043] 1) Since the overall petroleum hydrocarbon content of the oil-containing bleaching clay exceeds 25%, it needs to be added to the "pre-cleaning tank" along with a 0.1% aqueous solution of 15-crown ether-5 and water. The mixture is stirred and cleaned at room temperature for 4 hours. During this process, an oil separator is used to continuously remove the demulsified and floating oil and return it to the "recovery oil tank." The mass ratio of the 0.1% crown ether aqueous solution, bleaching clay, and water is 0.1:1:5.

[0044] 2) Add the extruded waste bleaching clay to the "washing tank," along with industrial water and a washing agent (mass ratio of nonylphenol polyoxyethylene ether NP-10: lauryl alcohol polyoxyethylene ether: sodium dodecylbenzenesulfonate = 17:2:1). Stir and heat to 70°C, and continue stirring for 60 minutes. Homogenize the washing agent, water, and oily bleaching clay, then wash the clay. After washing, drain the washing water and wash again using the same method. After two washings, filter the bleaching clay and air dry. The mass ratio of washing agent, bleaching clay, and water is 1:10:50.

[0045] 3) Combine the above-mentioned washing wastewater and add it to a separator. Then, add 12% (by weight of the total washing wastewater) of demulsifier (1% of a 0.1% crown ether aqueous solution, 50% sodium chloride, and 49% sodium sulfate) to the separator. Heat to 50 degrees Celsius and stir to form a mixture of oil and detergent. Use an oil separator to remove the upper oil layer. Then, add 10% (by weight of the remaining oil layer) of industrial ethanol to extract the detergent from the oil layer and dissolve it in an ethanol aqueous solution for reuse. The detergent is then collected in a washing liquid tank for use in the next washing mixture, thereby reducing operating costs.

[0046] 4) After separation, the crude oil is fed into a crude oil tank and mixed with other crude oils. After water removal, it is sent out. The wastewater solution after separation is treated in an oil-water separator and then recycled to reduce operating costs.

[0047] 5) The content of petroleum hydrocarbons in the washed bleached clay was determined to be 1.21% by infrared spectroscopy according to Appendix 0 of GB 5085.6, which specifies the determination of the total amount of recyclable petroleum hydrocarbons in solid waste. Therefore, it can be used in the brick-making industry or disposed of in ordinary landfills. Example

[0048] Target oily clay: Oily clay collected by a hazardous waste disposal company, details of which are shown in Table 3 below.

[0049] Table 3

[0050]

[0051] 1) Add the extruded waste bleaching clay to the "washing tank," along with industrial water and a washing agent (fatty alcohol polyoxyethylene ether AEO-9: lauryl alcohol polyoxyethylene ether: sodium dodecylbenzenesulfonate = 14:5:1). Stir and heat to 70°C, and continue stirring for 40 minutes. Homogenize the washing agent, water, and oily bleaching clay, then wash the clay. After washing, drain the washing water and wash again using the same method. After two washings, filter the bleaching clay and air dry. The mass ratio of washing agent, bleaching clay, and water is 1:10:40.

[0052] 2) Combine the above-mentioned washing wastewater and add it to a separator. Then, add 12% (by weight of the total washing wastewater) of demulsifier (1% of a 0.1% crown ether aqueous solution, 60% sodium chloride, and 39% sodium sulfate) to the separator. Heat to 50 degrees Celsius and stir to form a mixture of oil and detergent. Use an oil separator to remove the upper oil layer. Then, add 10% (by weight of the remaining oil layer) of industrial ethanol to extract the detergent from the oil layer and dissolve it in the ethanol for reuse. The detergent is then collected in a washing liquid tank for use in the next washing mixture, thereby reducing operating costs.

[0053] 3) After separation, the crude oil is mixed with other crude oils in a crude oil tank, and after water removal, it is sent out. The wastewater solution after separation is treated in an oil-water separator and then recycled to reduce operating costs.

[0054] 4) The washed mud and sand were tested by infrared spectroscopy according to Appendix 0 of GB 5085.6, which determines the total amount of recyclable petroleum hydrocarbons in solid waste. The petroleum hydrocarbon content in the washed white clay was 0.86%, and it can then be piled up and used in the construction industry such as brick making.

Claims

1. A method for harmlessly treating oily waste clay, characterized in that: Add detergent and water to the oily waste clay to be treated, and wash thoroughly 1-3 times under hydrophilic and oleophilic equilibrium conditions. After washing, separate the liquids and combine them with a demulsifier to form an oil-in-water flotation, thereby completing the three-phase separation of oil, detergent and water. The solid material after washing is harmless white clay. Add detergent and water to the oily waste bleaching clay to be treated, heat to 60-70℃ to cause the detergent in the system to produce a cloud point effect, accelerate the wetting and emulsification of oil in the bleaching clay into the washing liquid, wash thoroughly 1-2 times, collect the bleaching clay after washing, filter it with a plate filter, and air dry it to obtain harmless bleaching clay for safe discharge. The washing wastewater after washing is combined, and a demulsifier is added to form a mixed layer of oil and washing agent on the upper part of the washing water. The oil layer is collected after separation, and then solvent A is added to the oil layer to separate the washing agent of washing bleaching clay from the oil. The obtained washing agent is reused, and the separated oil is collected and reused. The demulsifier is a mixture of 1% by weight of a 0.1 wt% crown ether aqueous solution, 15-80% anhydrous sodium sulfate, and the balance sodium chloride. After mixing, it is added to the mixture and stirred at 35-55°C under heating conditions to form a demulsified state.

2. The method for harmless treatment of oily waste clay according to claim 1, characterized in that: When the oil content in the oily waste clay to be treated is greater than 25%, the oily waste clay to be treated is mixed with water and pre-washed with a crown ether aqueous solution with a concentration of 0.1 wt%, and then used; wherein, the mass ratio of clay to water is 1:5-20.

3. The method for harmless treatment of oily waste clay according to claim 1, characterized in that: The process involves adding detergent and water to the oily waste bleaching clay to be treated, mixing and stirring until homogeneous, and then, under balanced hydrophilic and oleophilic conditions, meeting the HLB 13-15 range, stirring and heating to 60-70℃, followed by stirring for 30-60 minutes for washing. This washing is repeated 1-2 times. After washing, the bleaching clay is collected, filtered using a plate filter, and air-dried to obtain harmless bleaching clay for safe discharge. The ratio of detergent, bleaching clay, and water is 1:10:30 to 1:10:

200.

4. The method for harmless treatment of oily waste clay according to claim 3, characterized in that: The detergent is one or more of the following: fatty alcohol polyoxyethylene ether AEO-7, fatty alcohol polyoxyethylene ether AEO-9, nonylphenol polyoxyethylene ether NP-9, nonylphenol polyoxyethylene ether NP-10, nonylphenol polyoxyethylene ether NP-15, sodium dodecylbenzenesulfonate, and lauryl alcohol polyoxyethylene ether.

5. The method for harmless treatment of oily waste clay according to claim 1, characterized in that: The amount of demulsifier added is 5-15% of the weight of the washing wastewater to be demulsified.

6. The method for harmless treatment of oily waste clay according to claim 1 or 4, characterized in that: Solvent A is one or more of ethanol, acetonitrile, and methanol.

7. The method for harmless treatment of oily waste clay according to claim 2, characterized in that: The 0.1 wt% crown ether aqueous solution used in the pre-cleaning process and the 0.1% crown ether aqueous solution used in the demulsifier are aqueous solutions containing 0.1% 15-crown ether-5.

8. The method for harmless treatment of oily waste clay according to claim 1, characterized in that: The water after the demulsification treatment is evaporated and recovered by an evaporation device and can be reused to wash the oily waste clay to be treated again.

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