A method for separating water and oil phases in the production process of ethionamide

Abstract

The application discloses a method for separating water and oil phases in an ethylthiambutene production process and relates to the technical field of water and oil separation. The method comprises the following steps: S1, mixing modified polyvinyl alcohol particles and anhydrous calcium chloride powder to obtain a water and oil separation agent; S2, adding the water and oil separation agent into a water and oil mixture and stirring to obtain a mixed liquid; and S3, adjusting the pH value of the mixed liquid to 4-5, filtering, and then standing for 1-2 days and layering. The water and oil separation agent comprises 50-60 parts of modified polyvinyl alcohol and 45-55 parts of anhydrous calcium chloride by weight. The weight ratio of the water and oil separation agent to the water and oil mixture is 5-13:1000. The method can increase the density of the water phase by adding the blend of modified PVA resin and calcium chloride into the water and oil mixture, promote the separation of the water and oil phases, and achieve the purpose of accelerating the water and oil separation.

Description

Technical Field

[0001] The present invention relates to the technical field of water-oil separation, and in particular to a method for separating water and oil phases in the production process of ethionamide. Background Art

[0002] In the past decade, the treatment of oily wastewater has attracted widespread attention.

[0003] Common oil-water separation methods include centrifugation, gravity, adsorption, coagulation and membrane separation.

[0004] At present, there are many methods for the actual production of water and oil separation:

[0005] 1. Air flotation separation

[0006] Flotation is a method of purifying water by forming tiny bubbles in water, carrying flocculants to the surface. This method requires that bubbles attached to oil droplets form oil-air particles. Because the presence of bubbles increases the density difference between water and particles, and because particle diameters are larger than crude oil droplets, using the density between particles instead of the oil density significantly increases the ascent velocity. Specifically, when a bubble (or multiple bubbles) attaches to an oil droplet, the vertical ascent velocity increases, enabling the removal of oil droplets much smaller than 50 μm in diameter.

[0007] 2. Gravity separation

[0008] Due to the different relative densities of oil, gas, and water, a certain oil-water mixture, under a certain pressure and temperature, will form a certain proportion of oil, gas, and water phases when the system is in equilibrium. When the lighter component is in laminar flow, the heavier component droplets settle according to the motion law of Stokes' equation. Gravity-type sedimentation separation equipment is designed based on this basic principle. Stokes' equation shows that the sedimentation rate is proportional to the square of the radius of the water in the oil, directly proportional to the density difference between water and oil, and inversely proportional to the viscosity of the oil. Increasing the water density, widening the oil-water density difference, and reducing the oil viscosity can increase the sedimentation separation rate, thereby improving separation efficiency.

[0009] 3. Centrifugal separation

[0010] Exploiting the difference in density between oil and water, the high-speed rotation of the oil-water mixture generates different centrifugal forces, thereby separating the oil and water. Because centrifugal equipment can reach very high rotational speeds, generating centrifugal forces hundreds of times the acceleration of gravity, they can separate the oil and water more thoroughly, requiring only a short residence time and a small device size. However, due to the moving parts, routine maintenance is difficult, and therefore, it is currently only used in laboratory analytical equipment and in locations requiring minimal floor space.

[0011] A key device operating on the principle of centrifugal separation is the hydrocyclone, used to physically separate a liquid (the continuous phase) from solid particles, droplets, or bubbles (the dispersed phase). The greater the density difference between the dispersed and continuous phases, the easier it is to separate the two phases. Similar to the situation in a gravitational field, for a given density difference between the two phases, the larger the particle diameter of the dispersed phase, the greater the difference in the reverse velocity between the two phases when equilibrium is reached in the gravitational field, and thus the easier it is to separate them.

[0012] 4. Electrolysis separation

[0013] As a final resort in oil-water treatment, electroevaporation is widely used in oil fields and refineries. Its principle is to subject an emulsion to a high-voltage AC or DC electric field. The electric field acts on water droplets, weakening the interfacial film strength of the emulsion, promoting collision and merging of the water droplets, ultimately coalescing into larger droplets that are separated from the crude oil. However, electroevaporation cannot be used independently to treat crude oil emulsions with high water content, as it can cause electrical breakdown and fail to establish the necessary inter-electrodeposition electric field strength. Therefore, electroevaporation cannot be used independently and must be used as a follow-up to other treatment methods.

[0014] Ethiocarbamate is an important thiocarbamate mineral flotation agent. Commonly used as a collector for non-ferrous metal sulfide ores, ethiocarbamate is an excellent collector for copper, lead, zinc, molybdenum, and nickel sulfides, offering advantages such as high selectivity and low usage. Furthermore, due to its weak capture ability for pyrite, it can be used to selectively capture copper from ores containing iron and copper sulfides. It can also be used for copper-molybdenum separation, copper-sulfur separation, and copper-lead separation. Ethiocarbamate is highly efficient, non-toxic, safe, and environmentally friendly, making it a pollution-free, environmentally friendly flotation agent for copper sulfide minerals, actively recommended by environmental protection departments worldwide. Ethiocarbamate also possesses certain foaming properties, making it suitable for both acidic and alkaline slurries. Its excellent overall performance contributes to both environmental protection and economic efficiency for mineral flotation companies. In recent years, ethiocarbamate has gained widespread favor in the global non-ferrous metal beneficiation industry, experiencing rapid growth in the mineral processing agent industry, with a wider application and growing demand.

[0015] According to the industry standard YS / T 357-2015, the moisture content of finished ethiocarbamate products must be ≤1%. This is a key concern for downstream customers. During the ethiocarbamate production process, the decolorization step involves a static separation of water and oil. This process is slow, requiring a long time, and significantly impacts production efficiency. Summary of the Invention

[0016] The purpose of the present invention is to overcome the above technical deficiencies and provide a method for separating the water and oil phases in the production process of ethylthiocarbamate, thereby solving the technical problem that the water and oil separation process in the production process of ethylthiocarbamate in the prior art takes a long time.

[0017] In order to achieve the above technical objectives, the technical solution of the present invention provides a method for separating water and oil phases in the production process of ethionamide, characterized in that it comprises the following steps:

[0018] S1: dry-mixing modified polyvinyl alcohol particles and anhydrous calcium chloride powder to obtain a water-oil separating agent;

[0019] S2: adding the water-oil separating agent to the water-oil mixture, stirring at a speed of 10 to 100 rpm for 2 to 3 hours to obtain a mixed liquid, wherein the water-oil mixture is a mixture of ethylthiocarbamate and water in the decolorization step of the ethylthiocarbamate production process;

[0020] S3: Adjust the pH value of the mixed liquid to 4-5, filter it, let it stand for 1-2 days, and separate the layers;

[0021] The water-oil separator comprises 50-60 parts of modified polyvinyl alcohol and 45-55 parts of anhydrous calcium chloride by weight. The weight ratio of the water-oil separator to the water-oil mixture is 5-13:1000. The particle size of the modified polyvinyl alcohol particles is 60 mesh, and the particle size of the anhydrous calcium chloride is 50-200 mesh.

[0022] The moisture absorption process of the modified PVA resin in the present invention mainly relies on gaseous water molecules to diffuse into the network interior. Calcium chloride condenses the gaseous water molecules into a liquid state, and then diffuses into the resin network interior. The gaseous water molecules and liquid water molecules have different effects on the resin network pore size when diffused into the modified PVA resin network interior: during the moisture absorption process, the preferential adsorption and aggregation of gaseous water molecules on the resin network outer surface cause the network pore size to decrease, making it difficult for external water molecules to diffuse into the interior. During the moisture absorption process, after the liquid water molecules enter the network interior, the resin network rapidly expands under the combined effects of hydrophilic groups, osmotic pressure, and electrostatic repulsion between ions, causing the network pore size to increase, which is conducive to the further entry of water molecules. Therefore, the water absorption capacity is generally higher than the moisture absorption capacity. Due to the extremely strong hydrophilicity of calcium chloride, the gaseous water molecules can be condensed into a liquid state before being absorbed by the resin network. After the modified PVA resin and calcium chloride are blended, they absorb water and become transparent and colloid-like. This is equivalent to water entering the interior of the modified PVA resin. The resin with a network structure can better lock in moisture. In addition, the higher density of calcium chloride, under the action of gravity, can effectively speed up the separation of water and oil.

[0023] Compared with the prior art, the present invention has the following beneficial effects: the water-oil separation method of the present invention adds a blend of modified PVA resin and calcium chloride to the water-oil mixture to be separated. On the one hand, the calcium chloride and the resin simultaneously absorb water, causing the resin to swell and have a certain water-restricting capacity. On the other hand, the addition of calcium chloride can increase the density of the water phase, promoting the separation of the two, thereby achieving the purpose of accelerating water-oil separation. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] Example 1

[0026] This specific embodiment provides a method for separating water and oil phases in the production process of ethionamide, characterized in that it includes the following steps:

[0027] S1: dry-mixing modified polyvinyl alcohol particles and anhydrous calcium chloride powder to obtain a water-oil separating agent;

[0028] S2: adding the water-oil separating agent to the water-oil mixture, stirring at a speed of 10 rpm for 2 hours to obtain a mixed liquid, wherein the water-oil mixture is a mixture of ethylthiocarbamate and water in the decolorization step of the ethylthiocarbamate production process;

[0029] S3: Adjust the pH value of the mixed liquid to 4, filter it, let it stand and separate it into layers;

[0030] The water-oil separator comprises 50 parts of modified polyvinyl alcohol and 45 parts of anhydrous calcium chloride by weight. The weight ratio of the water-oil separator to the water-oil mixture is 5:1000. The particle size of the modified polyvinyl alcohol particles is 60 mesh, and the particle size of the anhydrous calcium chloride is 200 mesh.

[0031] In this embodiment, the oil phase becomes clear after standing for 2 days. The water content in the oil phase is 0.5% as determined by Karl Fischer titration, which meets the requirements.

[0032] Example 2

[0033] This specific embodiment provides a method for separating water and oil phases in the production process of ethionamide, characterized in that it includes the following steps:

[0034] S1: dry-mixing modified polyvinyl alcohol particles and anhydrous calcium chloride powder to obtain a water-oil separating agent;

[0035] S2: adding the water-oil separating agent to the water-oil mixture at a speed of 100 rpm for 3 hours to obtain a mixed liquid, wherein the water-oil mixture is a mixture of ethylthiocarbamate and water in the decolorization step of the ethylthiocarbamate production process;

[0036] S3: Adjust the pH value of the mixed liquid to 5, filter it, let it stand and separate it into layers;

[0037] Among them, the water-oil separating agent includes 60 parts of modified polyvinyl alcohol and 55 parts of anhydrous calcium chloride by weight, the weight ratio of the water-oil separating agent and the water-oil mixture is 13:1000, the particle size of the modified polyvinyl alcohol particles is 60 mesh, and the particle size of the anhydrous calcium chloride is 50 mesh.

[0038] In this embodiment, the oil phase becomes clear after standing for 1 day. Karl Fischer water titration test shows that the water content in the oil phase is 0.3%, which meets the requirements.

[0039] Example 3

[0040] This specific embodiment provides a method for separating water and oil phases in the production process of ethionamide, characterized in that it includes the following steps:

[0041] S1: dry-mixing modified polyvinyl alcohol particles and anhydrous calcium chloride powder to obtain a water-oil separating agent;

[0042] S2: adding the water-oil separating agent to the water-oil mixture, stirring at a speed of 50 rpm for 2.5 hours to obtain a mixed liquid, wherein the water-oil mixture is a mixture of ethylthiocarbamate and water in the decolorization step of the ethylthiocarbamate production process;

[0043] S3: Adjust the pH value of the mixed liquid to 4.5, filter, let it stand and separate into layers;

[0044] The water-oil separator comprises 55 parts of modified polyvinyl alcohol and 50 parts of anhydrous calcium chloride by weight. The weight ratio of the water-oil separator to the water-oil mixture is 7:1000. The particle size of the modified polyvinyl alcohol particles is 60 mesh, and the particle size of the anhydrous calcium chloride is 100 mesh.

[0045] In this embodiment, the oil phase becomes clear after standing for 30 hours. The water content in the oil phase is 0.4% as determined by Karl Fischer titration, which meets the requirements.

[0046] Comparative Example 1

[0047] This comparative example is similar to Example 1, except that no calcium chloride is added in this comparative example.

[0048] Comparative Example 2

[0049] This comparative example is similar to Example 1, except that no modified PVA resin is added in this comparative example.

[0050] Comparative Example 3

[0051] This comparative example is similar to Example 1, except that the water-oil separating agent in this comparative example comprises 30 parts by weight of modified polyvinyl alcohol and 70 parts by weight of anhydrous calcium chloride.

[0052] Comparative Example 4

[0053] This comparative example is similar to Example 1, except that the weight ratio of the water-oil separating agent to the water-oil mixture in this comparative example is 20:1000.

[0054] The time for the oil to become clear in Comparative Examples 1 to 4 was 6 days, 4 days, 4 days, and 4 days. The water content in the oil phase was 1.8%, 1.5%, 1.2%, and 1.15% respectively as determined by Karl Fischer titration.

[0055] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for separating water and oil phases in the production process of ethionamide, characterized in that: The following steps are included: S1: dry-mixing modified polyvinyl alcohol particles and anhydrous calcium chloride powder to obtain a water-oil separator, wherein the particle size of the anhydrous calcium chloride is 50-200 mesh; S2: adding the water-oil separating agent to the water-oil mixture and stirring to obtain a mixed liquid; S3: Adjust the pH value of the mixed liquid to 4-5, filter, let it stand and separate into layers; The water-oil separator comprises 50-60 parts of modified polyvinyl alcohol and 45-55 parts of anhydrous calcium chloride in parts by weight, and the weight ratio of the water-oil separator to the water-oil mixture is 5-13:1000.

2. The method for water-oil phase separation according to claim 1, characterized in that The particle size of the modified polyvinyl alcohol particles is 60 meshes.

3. The method for water-oil phase separation according to claim 1, wherein The water-oil mixture is a mixture of ethylthiocarbamate and water in the decolorization process of ethylthiocarbamate production.

4. The method for water-oil phase separation according to claim 1, characterized in that: The stirring speed in step S2 is 10 to 100 rpm, and the stirring time is 2 to 3 hours.

5. The method for water-oil phase separation according to claim 4, characterized in that: The stratification time in step S3 is 1-2 days.