Continuous reaction system and method for co-producing solid sodium ethyl xanthate and liquid sodium ethyl xanthate

Abstract

The invention discloses a continuous reaction system and method for co-producing solid and liquid sodium ethyl xanthate, and relates to the technical field of sodium ethyl xanthate production. The system comprises a reaction kettle, a stirring motor, a raw material discharging pipe, an alkali liquor discharging pipe, a discharging pipe, a circulating liquid outlet pipeline, a centrifugal machine, a drying machine, a xanthate storage tank, a plurality of groups of control valves and a plurality of groups of backflow pipelines, which form a closed-loop reaction and separation system. The method comprises the following steps: feeding ethanol, carbon disulfide and caustic soda liquid with the concentration of more than or equal to 40% according to a molar ratio of 1: (0.9-1.2): (1.0-1.2), carrying out an initial reaction at 30-36 DEG C for 2.5-4.5 h, carrying out circulating separation, mother liquor recycling and continuous alkali supplementation to realize continuous production, and simultaneously producing liquid sodium ethyl xanthate and solid xanthate obtained by drying at 40-60 DEG C for 0.5-2.5 h. According to the method, reaction balance is promoted through high-concentration alkali, the raw material conversion rate is increased, the problem of solid precipitation is solved through the process of reaction-separation-recycling, product diversification is achieved, batch reaction is upgraded to continuous production, the productivity and stability are improved, and different market requirements are met.

Description

Technical Field

[0001] This invention relates to the field of sodium ethyl xanthate production technology, specifically disclosing a continuous reaction system and method for co-producing solid and liquid sodium ethyl xanthate. Background Technology

[0002] Sodium ethyl xanthate (commonly known as ethyl xanthate) is an important flotation collector. Its industrial production typically employs a process involving the reaction of alcohol, carbon disulfide, and sodium hydroxide in an aqueous solution. The traditional method is batch production, using a low concentration of liquid alkali (e.g., 30%), reacting for several hours at a strictly controlled temperature (e.g., 30-36°C) to obtain liquid sodium ethyl xanthate with a content of approximately 41%.

[0003] This traditional batch production method has the following significant limitations: Limited raw material conversion rate: Due to the limitation of reaction equilibrium, the reaction is not complete when using low concentration of alkali. There is a lot of room for improvement in the conversion rate of raw materials (especially high-value ethanol and carbon disulfide), which leads to waste of raw materials and increases production costs.

[0004] Limited product form: Traditional processes can only produce liquid sodium ethyl xanthate, which cannot meet the market demand for high-purity solid xanthate that is easy to transport and store over long distances, thus limiting the product's application scenarios and market competitiveness.

[0005] Low production efficiency: In batch reaction mode, the reaction time is long, and the reaction rate slows down significantly in the later stage of the reaction due to the accumulation of by-products and the decrease in reactant concentration, which further reduces the production capacity per unit time. Production efficiency urgently needs to be improved.

[0006] To improve the conversion rate of raw materials, those skilled in the art would readily consider increasing the concentration of reactants, such as using high-concentration liquid alkali (e.g., 40% or higher). However, this approach directly leads to the precipitation of large quantities of sodium ethyl xanthate in the reaction system due to reduced solubility. These solid products coat unreacted raw materials, hindering effective contact between them, and also adhere to the inner wall of the reactor and the stirring shaft, severely impeding the continuation of the reaction. In extreme cases, this can even cause the stirrer to seize, rendering the reaction system unusable. Therefore, how to maintain the continuous and efficient progress of the reaction under high-concentration alkali conditions has long been an unsolved technical problem in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a continuous reaction system and method for co-producing solid and liquid sodium ethyl xanthate, which solves the technical problems of low raw material conversion rate, single product form, low production efficiency, and solid precipitation hindering the reaction under high-concentration alkali processes in traditional production processes.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A continuous reaction system for co-producing solid and liquid sodium ethyl xanthate includes a reactor. A stirring motor is installed above the reactor. The main shaft of the stirring motor passes through the top cover of the stirring motor and is connected to a stirring paddle. A raw material feed pipe and an alkali feed pipe communicating with the inner cavity of the reactor are installed on the top cover of the reactor. The discharge port at the bottom of the reactor is connected to a discharge pipe and a circulating liquid discharge pipe. A first control valve is installed on the discharge port. The circulating liquid discharge pipe is connected to a centrifuge through a circulating conveying pump. A conveyor belt is installed at the discharge port of the centrifuge. A dryer is installed at the discharge port of the conveyor belt. The discharge pipe is connected to a xanthate storage tank through a conveying pump.

[0009] Furthermore, the centrifuge outlet is connected to a mother liquor transfer pump, a second control valve is installed on the centrifuge outlet, and a mother liquor return pipe is installed at the outlet of the mother liquor transfer pump. The mother liquor return pipe passes through the top cover of the reactor and is connected to the inner cavity of the reactor.

[0010] Furthermore, the top cover of the reactor is also equipped with a tail gas pipe that is connected to the inner cavity of the reactor, and the outlet of the tail gas pipe is connected to the tail gas system.

[0011] Furthermore, a nitrogen pipeline connected to the inner cavity of the reactor is installed on the top cover of the reactor. The inlet of the nitrogen pipeline is connected to a nitrogen source, and a third control valve is installed on the nitrogen pipeline.

[0012] Furthermore, a fourth control valve is installed on the discharge pipe.

[0013] Furthermore, a fifth control valve is installed on the circulating liquid outlet pipeline between the circulating pump and the reactor discharge port.

[0014] Furthermore, a sixth control valve is installed on the circulating liquid outlet pipeline between the circulating transfer pump and the centrifuge.

[0015] A continuous reaction method for co-producing solid and liquid sodium ethyl xanthate includes the following steps: Step 1. Feeding and Initialization Reaction: Ethanol, carbon disulfide, and liquid alkali are added to the reactor in a molar ratio of 1:0.9-1.2:1.0-1.2 to carry out the initialization reaction. The concentration of the liquid alkali is ≥40%. Step 2. Cyclic reaction and separation: After initial reaction for 2.5h-4.5h, open the first control valve and the fifth control valve. The reaction vessel discharges the reaction liquid containing particulate sodium ethyl xanthate through the discharge port. The reaction liquid is sent into a centrifuge for separation to obtain aqueous solid sodium ethyl xanthate and mother liquor. Step 3. Reuse of Filtration Mother Liquor and Collection of Solid Xanthate Product: The filtration mother liquor obtained in Step 2 is returned to the reactor through the mother liquor return pipeline by the mother liquor transfer pump to continue participating in the reaction. The aqueous solid sodium ethyl xanthate obtained in Step 2 is conveyed into the dryer by the conveyor belt and dried to obtain the solid xanthate product. The drying conditions in the dryer are: drying temperature 40℃-60℃, drying time 0.5h-2.5h. Step 4. Continuous feeding and discharging: While performing Step 2 and Step 3, continue to add liquid alkali to the reactor. During this period, maintain the volume of the reactants in the reactor at 75%-95% of the volume of the reactants during the initial reaction in Step 1 until the reaction is completed. The liquid sodium ethyl xanthate in the reactor is then transferred to the xanthate storage tank for storage. Step 5. After the liquid alkali is added, let it react for another 0.5-1.0 hours, during which time the centrifuge will run continuously.

[0016] Furthermore, in step 1, the addition of ethanol, carbon disulfide, and liquid alkali is as follows: first, add ethanol and carbon disulfide to the reactor at once, then start stirring the reactor. At the same time, 5℃-10℃ cooling water is circulated into the jacket of the reactor. After circulating the cooling water, liquid alkali is added dropwise into the reactor. The filling rate of the reactor is 65%-75%, and the reaction temperature in the reactor is controlled at 30℃-36℃.

[0017] The beneficial effects of this invention are: 1. By using high-concentration liquid alkali, the reaction equilibrium is shifted to the right, significantly improving the conversion rate of raw materials (especially ethanol and carbon disulfide), reducing the residue of free carbon disulfide from the source, and improving product safety and quality.

[0018] 2. Through the cyclical operation of "reaction-discharge-separation-reuse", the precipitated solid products are actively and promptly removed from the reaction system, avoiding the inhibitory effect of solid accumulation on the reaction and enabling the high-concentration alkali process to be implemented smoothly.

[0019] 3. A single system can simultaneously produce high-purity solid xanthate and conventional liquid sodium ethyl xanthate, meeting the needs of different customers and enhancing market competitiveness. Solid products are easier to store and transport over long distances.

[0020] 4. This method enables the transformation from batch reaction to semi-continuous / continuous production, resulting in a more stable reaction process and increased production capacity per unit time. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system of the present invention; Figure 2 This is a process flow diagram of the present invention.

[0022] In the diagram: 1. Reactor; 2. Centrifuge; 3. Dryer; 4. Transfer pump; 5. Circulating transfer pump; 6. Stirring motor; 7. Mother liquor transfer pump; 8. Nitrogen pipeline; 10. Liquid alkali discharge pipe; 11. Tail gas pipeline; 12. Mother liquor return pipeline; 13. Main shaft; 14. Discharge pipe; 15. Circulating liquid discharge pipe; 17. Conveyor belt; 18. Raw material discharge pipe; 19. Discharge port; 20. First control valve; 21. Xanthate storage tank; 22. Second control valve; 23. Third control valve; 24. Fourth control valve; 25. Fifth control valve; 26. Sixth control valve. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the invention.

[0024] Example 1 Implementation conditions: Reactor 1 is a 5m³ reactor, and the reaction environment is summer.

[0025] A continuous reaction method for co-producing solid and liquid sodium ethyl xanthate includes the following steps: Step 1. Feeding and Initialization Reaction: Prepare 0.736 tons of ethanol, 1.113 tons of carbon disulfide and 1.611 tons of 40% alkali solution. First, add 0.736 tons of ethanol and 1.113 tons of carbon disulfide into reactor 1 at once. Then, start stirring reactor 1. At the same time, 5°C cooling water is circulated into the jacket of reactor 1. After circulating the cooling water, add alkali solution dropwise into reactor 1. The filling rate of reactor 1 is 67.5%. The reaction temperature in reactor 1 is controlled at 30°C. Step 2. Cyclic reaction and separation: After initializing the reaction for 3.5 hours, open the first control valve 20 and the fifth control valve 25. The reaction vessel 1 discharges the reaction liquid containing particulate sodium ethyl xanthate suspension through the discharge port 19. The reaction liquid is sent into the centrifuge 2 for separation to obtain aqueous solid sodium ethyl xanthate with a sodium ethyl xanthate content of 74.7% and the mother liquor of filtration. Step 3. Reuse of Filtration Mother Liquor and Collection of Solid Xanthate Product: The filtration mother liquor obtained in Step 2 is returned to the reaction vessel 1 through the mother liquor return pipe 12 under the action of the mother liquor transfer pump 7 to continue participating in the reaction. The aqueous solid sodium ethyl xanthate obtained in Step 2 is conveyed into the dryer 3 through the conveyor belt 17 and dried to obtain a solid xanthate product with a sodium ethyl xanthate content of 89.2%. The drying conditions in the dryer 3 are: drying temperature 55℃, drying time 2.0h. Step 4. Continuous feeding and discharging: While performing Step 2 and Step 3, continue to add liquid alkali to reactor 1. During this period, maintain the volume of the reactants in reactor 1 at 88% of the volume at which the reactants in reactor 1 were initialized in Step 1 until the reaction is completed. The remaining liquid xanthate product with a sodium ethyl xanthate content of 31.9% in reactor 1 is then transported to xanthate storage tank 21 for storage. Step 5. After the liquid alkali is added, let it react for another 0.8 hours. During this time, centrifuge 2 will continue to run.

[0026] Example 2 Implementation conditions: Reactor 1 is a 1m³ reactor, and the reaction environment is winter.

[0027] A continuous reaction method for co-producing solid and liquid sodium ethyl xanthate includes the following steps: Step 1. Feeding and initial reaction: Prepare 0.147 tons of ethanol, 0.257 tons of carbon disulfide and 0.302 tons of 45% liquid alkali (molar ratio of approximately 1:1.1:1.13). First, add the ethanol and carbon disulfide into reactor 1 at once, then start stirring reactor 1. At the same time, 10℃ cooling water is circulated into the jacket of reactor 1. After circulating the cooling water, add liquid alkali dropwise into reactor 1. The filling rate of reactor 1 is 68%, and the reaction temperature in reactor 1 is controlled at 32℃. Step 2. Cyclic reaction and separation: After initial reaction for 3.0 h, open the first control valve 20 and the fifth control valve 25. The reaction vessel 1 discharges the reaction liquid containing particulate sodium ethyl xanthate suspension through the discharge port 19. The reaction liquid is sent into the centrifuge 2 for separation to obtain aqueous solid sodium ethyl xanthate with a sodium ethyl xanthate content of 76.5% and the mother liquor of filtration. Step 3. Reuse of Filtration Mother Liquor and Collection of Solid Xanthate Product: The filtration mother liquor obtained in Step 2 is returned to the reaction vessel 1 through the mother liquor return pipe 12 under the action of the mother liquor transfer pump 7 to continue participating in the reaction. The aqueous solid sodium ethyl xanthate obtained in Step 2 is conveyed into the dryer 3 through the conveyor belt 17 and dried to obtain a solid xanthate product with a sodium ethyl xanthate content of 88%. The drying conditions in the dryer 3 are: drying temperature 53℃, drying time 1.4h. Step 4. Continuous feeding and discharging: While performing Step 2 and Step 3, continue to add liquid alkali to reactor 1. During this period, maintain the volume of the reactants in reactor 1 at 85% of the volume at which the reactants in reactor 1 were initialized in Step 1 until the reaction is completed. The remaining liquid xanthate product with a sodium ethyl xanthate content of 32.34% in reactor 1 is then transported to xanthate storage tank 21 for storage. Step 5. After the liquid alkali is added, let it react for another 0.7 hours. During this time, centrifuge 2 will continue to run.

[0028] Example 3 Implementation conditions: Reactor 1 is a 0.5m³ reactor, and the reaction environment is summer.

[0029] A continuous reaction method for co-producing solid and liquid sodium ethyl xanthate includes the following steps: Step 1. Feeding and Initialization Reaction: Prepare 0.074 tons of ethanol, 0.124 tons of carbon disulfide and 0.127 tons of 50% alkali solution (molar ratio approximately 1:1.05:1.05). First, add the ethanol and carbon disulfide into reactor 1 at once, then start stirring reactor 1. At the same time, 5℃ cooling water is circulated into the jacket of reactor 1. After circulating the cooling water, add 50% alkali solution dropwise into reactor 1. The filling rate of reactor 1 is 70%, and the reaction temperature in reactor 1 is controlled at 34℃. Step 2. Cyclic reaction and separation: After initializing the reaction for 2.5 hours, open the first control valve 20 and the fifth control valve 25. The reaction vessel 1 discharges the reaction liquid containing particulate sodium ethyl xanthate suspension through the discharge port 19. The reaction liquid is sent into the centrifuge 2 for separation to obtain aqueous solid sodium ethyl xanthate with a sodium ethyl xanthate content of 78.2% and the mother liquor of filtration. Step 3. Reuse of Filtration Mother Liquor and Collection of Solid Xanthate Product: The filtration mother liquor obtained in Step 2 is returned to the reaction vessel 1 through the mother liquor return pipe 12 under the action of the mother liquor transfer pump 7 to continue participating in the reaction. The aqueous solid sodium ethyl xanthate obtained in Step 2 is conveyed into the dryer 3 through the conveyor belt 17 and dried to obtain a solid xanthate product with a sodium ethyl xanthate content of 90%. The drying conditions in the dryer 3 are: drying temperature 45℃, drying time 2.0h. Step 4. Continuous feeding and discharging: While performing Step 2 and Step 3, continue to add liquid alkali to reactor 1. During this period, maintain the volume of the reactants in reactor 1 at 82% of the volume of the reactants in reactor 1 during the initial reaction in Step 1 until the reaction is completed. The remaining liquid xanthate product with a sodium ethyl xanthate content of 33% in reactor 1 is then transported to xanthate storage tank 21 for storage. Step 5. After the liquid alkali is added, let it react for another 0.6 hours. During this time, centrifuge 2 will continue to run.

[0030] This invention solves the technical problem of solid product precipitation hindering the reaction under high-concentration alkaline conditions, and realizes the co-production of solid and liquid sodium ethyl xanthate. The solid product content is greater than 85%, the liquid product content is about 30%, and the total conversion rate of raw material carbon disulfide is increased by about 15% compared with the traditional process, thereby improving production efficiency and product added value.

[0031] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A continuous reaction system for the co-production of solid and liquid sodium ethyl xanthate, characterized in that, The reactor includes a reactor (1), a stirring motor (6) is installed above the reactor (1), the main shaft (13) of the stirring motor (6) passes through the top cover of the stirring motor (6) and is connected to a stirring paddle, the top cover of the reactor (1) is equipped with a raw material feeding pipe (18) and an alkali feeding pipe (10) that are connected to the inner cavity of the reactor (1), the discharge port (19) at the bottom of the reactor (1) is connected to a discharge pipe (14) and a circulating liquid discharge pipe (15), a first control valve (20) is installed on the discharge port (19), the circulating liquid discharge pipe (15) is connected to a centrifuge (2) through a circulating conveying pump (5), the discharge port of the centrifuge (2) is equipped with a conveyor belt (17), the discharge port of the conveyor belt (17) is equipped with a dryer (3), and the discharge pipe (14) is connected to a xanthate storage tank (21) through a conveying pump (4).

2. The continuous reaction system for co-producing solid and liquid sodium ethyl xanthate according to claim 1, characterized in that, The centrifuge (2) is connected to a mother liquor transfer pump (7) at its outlet. A second control valve (22) is installed on the outlet of the centrifuge (2). A mother liquor return pipe (12) is installed at the outlet of the mother liquor transfer pump (7). The mother liquor return pipe (12) passes through the top cover of the reactor (1) and is connected to the inner cavity of the reactor (1).

3. The continuous reaction system for co-producing solid and liquid sodium ethyl xanthate according to claim 2, characterized in that, The top cover of the reactor (1) is also equipped with a tail gas pipe (11) that is connected to the inner cavity of the reactor (1), and the outlet of the tail gas pipe (11) is connected to the tail gas system.

4. The continuous reaction system for co-producing solid and liquid sodium ethyl xanthate according to claim 3, characterized in that, The top cover of the reactor (1) is also equipped with a nitrogen pipeline (8) that is connected to the inner cavity of the reactor (1). The inlet of the nitrogen pipeline (8) is connected to the nitrogen source, and a third control valve (23) is installed on the nitrogen pipeline (8).

5. The continuous reaction system for co-producing solid and liquid sodium ethyl xanthate according to claim 4, characterized in that, A fourth control valve (24) is installed on the discharge pipe (14).

6. The continuous reaction system for co-producing solid and liquid sodium ethyl xanthate according to claim 5, characterized in that, A fifth control valve (25) is installed on the circulating liquid outlet pipe (15) between the circulating pump (5) and the discharge port of the reactor (1).

7. The continuous reaction system for co-producing solid and liquid sodium ethyl xanthate according to claim 6, characterized in that, A sixth control valve (26) is installed on the circulating discharge pipe (15) between the circulating transfer pump (5) and the centrifuge (2).

8. The continuous reaction method for co-producing solid and liquid sodium ethyl xanthate according to claim 1, characterized in that, Includes the following steps: Step 1. Feeding and initialization reaction: Ethanol, carbon disulfide and liquid alkali are added to the reaction vessel (1) in a molar ratio of 1:0.9-1.2:1.0-1.2 to carry out the initialization reaction. The concentration of the liquid alkali is ≥40%. Step 2. Cyclic reaction and separation: After initializing the reaction for 2.5h-4.5h, open the first control valve (20) and the fifth control valve (25). The reaction vessel (1) discharges the reaction liquid containing particulate sodium ethyl xanthate through the discharge port (19). The reaction liquid is sent into the centrifuge (2) for separation to obtain aqueous solid sodium ethyl xanthate and mother liquor. Step 3. Reuse of Filtration Mother Liquor and Collection of Solid Xanthate Product: The filtration mother liquor obtained in Step 2 is returned to the reactor (1) through the mother liquor return pipe (12) under the action of the mother liquor transfer pump (7) to continue participating in the reaction. The aqueous solid sodium ethyl xanthate obtained in Step 2 is transported into the dryer (3) through the conveyor belt (17) and dried to obtain the solid xanthate product. The drying conditions in the dryer (3) are: drying temperature 40℃-60℃, drying time 0.5h-2.5h; Step 4. Continuous feeding and discharging: While performing Step 2 and Step 3, continue to add liquid alkali to the reactor (1). During this period, maintain the volume of the reactant in the reactor (1) at 75%-95% of the volume of the reactant in the reactor (1) during the initial reaction in Step 1 until the reaction is completed. The liquid sodium ethyl xanthate in the reactor (1) is then transported to the xanthate storage tank (21) for storage. Step 5. After the liquid alkali is added, the reaction continues for 0.5h-1.0h. During this period, the centrifuge (2) continues to run.

9. The continuous reaction method for co-producing solid and liquid sodium ethyl xanthate according to claim 8, characterized in that, In step 1, the addition of ethanol, carbon disulfide and liquid alkali is as follows: first, add ethanol and carbon disulfide to the reactor (1) at one time, then start the reactor (1) to stir, and at the same time, 5℃-10℃ condensing water is introduced into the jacket of the reactor (1). After introducing the condensing water, liquid alkali is added dropwise into the reactor (1). The filling rate of the reactor (1) is 65%-75%, and the reaction temperature in the reactor (1) is controlled at 30℃-36℃.

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