Efficient evaporative crystallization method for calcium formate

Abstract

The invention relates to the technical field of calcium formate production, in particular to a calcium formate efficient evaporative crystallization method which comprises the following steps: S1, mixing reaction; s2, removing impurities; s3, evaporative crystallization; s4, centrifugal drying; and S5, cooling and packaging. The method has the advantages that the whole process is simple, the production cost and the labor intensity are reduced, large-scale continuous production is easy to realize, the content of the produced calcium formate product is 99% or above, the purity is high, and the color is pure white; the triple-effect evaporation technology is adopted, energy consumption is reduced, the effects of energy conservation and emission reduction are achieved, meanwhile, crystals which are evenly distributed and large in particle size can be obtained through the last-effect DTB crystallizer, follow-up filtering and drying are facilitated, and energy consumption in the follow-up process can be greatly reduced; in the packaging process, the crystals are introduced into a cooler to be cooled and then conveyed to a cooling cyclone separator, the temperature of the crystals is reduced to 40 DEG C, it is guaranteed that particles are uniform and cannot be hardened, the quality is optimized, and the operation safety degree is also improved.

Description

Technical Field

[0001] The invention relates to the technical field of calcium formate production, and in particular to a method for efficiently evaporating and crystallizing calcium formate. Background Art

[0002] Calcium formate, also known as calcium formate, is a calcium salt containing formic acid. As a new type of feed additive newly developed in China, calcium formate has a wide range of uses. It can be used as an acidulant to replace citric acid and fumaric acid, and can also be widely used in industrial production such as food, chemical industry, and building materials. In addition, calcium formate is a water-soluble mineral salt with great nutritional value. It can be added to food to supplement the calcium ions needed by the human body. In recent years, calcium formate, as a new type of feed additive, can be used as an acidulant to replace citric acid and fumaric acid, and can also replace calcium propionate as a preservative and mildew preventer. It is used in various animal feeds and has the functions of preventing diarrhea and dysentery and helping feed digestion and absorption. Due to the excellent performance and low price of calcium formate products, it currently has a good market at home and abroad and has broad sales prospects.

[0003] In the prior art, the evaporation, concentration and crystallization steps all adopt single-effect evaporation and crystallization equipment. Such equipment has high energy consumption, large amount of evaporated water discharge, high discharge temperature of evaporated water and condensed water during the production process, serious heat energy loss, low heat energy utilization rate, large consumption of cooling water for treating evaporated water, high environmental protection cost, and lacks a purification step for the synthetic liquid. Impurities such as heavy metals, arsenic, and calcium carbonate are easily left in the raw materials, making it difficult to ensure the quality of the product. Therefore, the present invention proposes an evaporation and crystallization process for calcium formate production to solve the problems existing in the prior art. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a high-efficiency evaporation and crystallization method of calcium formate.

[0005] The present invention is achieved through the following technical scheme: The present invention discloses a method for efficient evaporation and crystallization of calcium formate, comprising the following steps:

[0006] S1. Mixed reaction

[0007] A first reactor, a second reactor and a third reactor are used, formic acid solution and calcium carbonate powder are continuously added into the first reactor and stirred evenly for reaction, the reaction material at the bottom of the first reactor is pressed into the second reactor from the bottom of the second reactor by pressure, the reaction material at the top of the second reactor overflows into the third reactor, the generated high-concentration calcium formate material gathers at the bottom of the third reactor 130, and water-insoluble impurities float on the top of the third reactor;

[0008] S2. Remove impurities

[0009] The synthetic liquid is discharged into a purification kettle, and first heated to 900°C at 101.325 kPa to remove calcium carbonate in the synthetic liquid. Then, after the synthetic liquid is cooled, heavy metal capture microspheres are prepared to precipitate and remove heavy metals in the synthetic liquid.

[0010] S3, evaporation crystallization

[0011] The filtered trihydroxy condensation liquid is subjected to multi-stage dehydration by a triple-effect evaporator crystallizer. The triple-effect evaporator removes part of the water in the trihydroxy condensation liquid, the second-effect evaporator concentrates the trihydroxy condensation liquid to a saturated state, and the first-effect evaporator controls the crystallization of calcium formate, so that 80% to 90% of the mass percentage of calcium formate is precipitated and crystallized;

[0012] S4, centrifugal drying

[0013] The discharge from the first-effect evaporator is sent to the centrifuge for solid-liquid separation. The liquid enters the sedimentation process, and the crystals are transported to the airflow dryer through the screw feeder. The airflow contacts the crystals and evaporates the water, and then enters the packaging process.

[0014] S5. Cooling packaging

[0015] In the packaging process, the crystals are first passed into a cooler for cooling, and then transported to a cooling cyclone separator to reduce the crystal temperature to 40°C and uniformly form product particles for packaging.

[0016] As an improvement, the concentration of the formic acid solution used is 85-95%, the purity of calcium carbonate is greater than 95%, the weight ratio of the formic acid solution added to the first reactor to the calcium carbonate powder is (1.03-1.15):1, the material temperature in each reactor is 30-50°C, and the pH value in each reactor is 3.5-4.

[0017] As an improvement, in step S2, calcium carbonate in the synthetic liquid is removed by heating, and the calcium carbonate is decomposed into calcium oxide and carbon dioxide. The calcium oxide remains in the synthetic liquid and continues to participate in the reaction, while the carbon dioxide escapes.

[0018] As an improvement, in step S3, the triple-effect evaporation crystallizer controls the evaporation rate to 1.5 m / s. 3 / h~2.5m 3 / h, the second-effect evaporator controls the evaporation rate to 2.4m 3 / h, the first-effect evaporator controls the crystallization of calcium formate, so that 85% by mass of calcium formate is precipitated and crystallized.

[0019] As an improvement, formic acid solution and calcium carbonate powder are added into the first reactor to start the reaction. The reaction materials in the first reactor contain unreacted formic acid and calcium carbonate, calcium formate generated by the reaction, water brought in by the formic acid solution and reaction by-products, and impurities brought in by the calcium carbonate powder. The reaction materials continue to react while being pressed into the second reactor from the bottom of the first reactor by the liquid level difference. After entering the second reactor, the reaction materials flow from bottom to top and overflow from the upper part of the second reactor into the third reactor. The chemical reaction in the third reactor has been basically completed, and the high-concentration calcium formate material generated gathers at the bottom of the third reactor, and water-insoluble impurities float on the upper part of the third reactor.

[0020] The advantages of the present invention compared with the prior art are:

[0021] 1. The overall process is simple, the production efficiency is high, the product quality is good, the production cost and labor intensity are reduced, it is easy to realize large-scale continuous production, and it is suitable for wide promotion and application. It has been verified that the content of the produced calcium formate product is more than 99%, the purity is high, and the color is pure white;

[0022] Second, the triple-effect evaporation technology is used to fully utilize the thermal efficiency of steam, reduce the amount of heating steam, reduce the amount of steam discharged, reduce energy consumption, and play a role in energy conservation and emission reduction. At the same time, the final-effect DTB crystallizer is conducive to obtaining uniformly distributed crystals with larger particle size, which is conducive to subsequent filtration and drying, and can greatly reduce the energy consumption of subsequent processes. It is conducive to the evaporation of inorganic salt materials in saturated solutions, and is not easy to form scars and scale, making the system more stable;

[0023] 3. In the packaging process, the crystals are passed into a cooler for cooling, and then transported to a cooling cyclone separator to reduce the crystal temperature to 40°C, ensuring that the particles are uniform and not agglomerated, optimizing quality, and improving operational safety. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] The present application fully explains the problems of the prior art in the technical background, and there are no superordinate or general problems. The problems to be solved by the present application are described in detail in the following invention content and specific implementation methods, the technical problems to be solved by the technical scheme are clarified, and it is determined that the technical scheme of the present application has beneficial effects relative to the objective prior art.

[0026] The first embodiment provided is as follows:

[0027] The concentration of the formic acid solution used is 80, the purity of calcium carbonate is greater than 95%, the weight ratio of the formic acid solution added to the first reactor to the calcium carbonate powder is 1.03:1, the material temperature in each reactor is 30°C, and the pH value in each reactor is 3.5. A method for efficient evaporation and crystallization of calcium formate, comprising the following steps:

[0028] S1. Mixed reaction

[0029] A first reactor, a second reactor and a third reactor are used, formic acid solution and calcium carbonate powder are continuously added into the first reactor and stirred evenly for reaction, the reaction material at the bottom of the first reactor is pressed into the second reactor from the bottom of the second reactor by pressure, the reaction material at the top of the second reactor overflows into the third reactor, the generated high-concentration calcium formate material gathers at the bottom of the third reactor 130, and water-insoluble impurities float on the top of the third reactor;

[0030] S2. Remove impurities

[0031] The synthetic liquid is discharged into a purification kettle, and first heated to 900°C at 101.325 kPa to remove calcium carbonate in the synthetic liquid. Then, after the synthetic liquid is cooled, heavy metal capture microspheres are prepared to precipitate and remove heavy metals in the synthetic liquid.

[0032] In step S2, calcium carbonate in the synthetic liquid is removed by heating, and the calcium carbonate is decomposed into calcium oxide and carbon dioxide. The calcium oxide remains in the synthetic liquid and continues to participate in the reaction, while the carbon dioxide escapes.

[0033] S3, evaporation crystallization

[0034] The filtered trihydroxy condensation liquid is subjected to multi-stage dehydration by a triple-effect evaporator crystallizer. The triple-effect evaporator removes part of the water in the trihydroxy condensation liquid, the second-effect evaporator concentrates the trihydroxy condensation liquid to a saturated state, and the first-effect evaporator controls the crystallization of calcium formate so that 80% of the mass percentage of calcium formate is precipitated and crystallized;

[0035] Further optimization, the triple-effect evaporation crystallizer controls the evaporation speed to 1.5m 3 / h, the second-effect evaporator controls the evaporation rate to 2.4m 3 / h, the first-effect evaporator controls the crystallization of calcium formate, so that 80% of the mass percentage of calcium formate is precipitated and crystallized.

[0036] S4, centrifugal drying

[0037] The discharge from the first-effect evaporator is sent to the centrifuge for solid-liquid separation. The liquid enters the sedimentation process, and the crystals are transported to the airflow dryer through the screw feeder. The airflow contacts the crystals and evaporates the water, and then enters the packaging process.

[0038] S5. Cooling packaging

[0039] In the packaging process, the crystals are first passed into a cooler for cooling, and then transported to a cooling cyclone separator to reduce the crystal temperature to 40°C and uniformly form product particles for packaging.

[0040] The implementation provided is as follows:

[0041] The concentration of the formic acid solution used is 95, the purity of calcium carbonate is greater than 95%, the weight ratio of the formic acid solution added to the first reactor to the calcium carbonate powder is 1.15:1, the material temperature in each reactor is 50°C, and the pH value in each reactor is 4.

[0042] Adding formic acid solution and calcium carbonate powder into a first reactor to start reaction, the reaction material in the first reactor contains unreacted formic acid and calcium carbonate, calcium formate generated by the reaction, water brought in by the formic acid solution and reaction byproducts, and impurities brought in by the calcium carbonate powder, the reaction material continues to react while being pressed into the second reactor from the bottom of the first reactor by the liquid level difference, after entering the second reactor, the reaction material flows from bottom to top and overflows from the upper part of the second reactor into the third reactor, the chemical reaction in the third reactor has been basically completed, the generated high-concentration calcium formate material gathers at the bottom of the third reactor, and the water-insoluble impurities float on the upper part of the third reactor;

[0043] Further optimization, the stirring speed of the stirrer in the first reactor and the second reactor is usually 60r / min, the stirring speed in the third reactor is 40-60r / min, the stirring speed in the third reactor is appropriately reduced, and the temperature of the steam introduced into the heating coil is controlled so that the reaction temperature in each reactor reaches 35-50°C;

[0044] The upper reaction material overflows from the upper part of the third reactor, and the bottom reaction material is collected from the bottom of the third reactor. The bottom reaction material mainly contains calcium formate, formic acid and water. A crude calcium formate product and a mother liquor are separated from the bottom reaction material. The crude calcium formate product is dried and sieved to obtain a calcium formate product.

[0045] The upper reaction materials are mainly formic acid, water, a small amount of calcium formate, and floating water-insoluble impurities. The entrained water-insoluble impurities are separated from the upper reaction materials to obtain a liquid phase.

[0046] A portion of the liquid phase is returned to the first reactor and / or the second reactor and / or the third reactor, and a portion of the liquid phase is discharged into the purification kettle, first heated to 900°C at 101.325 kPa to remove calcium carbonate in the synthetic liquid, and then after the synthetic liquid is cooled, heavy metal capture microspheres are prepared to precipitate and remove heavy metals in the synthetic liquid; the calcium carbonate in the synthetic liquid is heated to remove the calcium carbonate, and the calcium carbonate is decomposed into calcium oxide and carbon dioxide. The calcium oxide remains in the synthetic liquid to continue to participate in the reaction, and the carbon dioxide escapes.

[0047] The filtered trihydroxy condensation liquid is subjected to multi-stage dehydration by a triple-effect evaporator crystallizer. The triple-effect evaporator removes part of the water in the trihydroxy condensation liquid, the second-effect evaporator concentrates the trihydroxy condensation liquid to a saturated state, and the first-effect evaporator controls the crystallization of calcium formate, so that 85% by mass of calcium formate is precipitated and crystallized;

[0048] The triple-effect evaporation crystallizer controls the evaporation speed to 2.5m 3 / h, the second-effect evaporator controls the evaporation rate to 2.4m 3 / h, the first-effect evaporator controls the crystallization of calcium formate, so that 85% by mass of calcium formate is precipitated and crystallized.

[0049] The discharge from the first-effect evaporator is sent to the centrifuge for solid-liquid separation. The liquid enters the sedimentation process, and the crystals are transported to the airflow dryer through the screw feeder. The airflow contacts the crystals and evaporates the water, and then enters the packaging process.

[0050] In the packaging process, the crystals are first passed into a cooler for cooling, and then transported to a cooling cyclone separator to reduce the crystal temperature to 40°C and uniformly form product particles for packaging.

[0051] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope of the present application is indicated by the claims.

[0052] It should be understood that the present application is not limited to the above description, and various modifications and changes can be made without departing from its scope. The above-described embodiments of the present application do not constitute a limitation on the scope of protection of the present application.

Claims

1. A calcium formate efficient evaporation crystallization method, characterized in that: The following steps are involved: S1. Mixed reaction A first reactor, a second reactor and a third reactor are used, formic acid solution and calcium carbonate powder are continuously added into the first reactor and stirred evenly for reaction, the reaction material at the bottom of the first reactor is pressed into the second reactor from the bottom of the second reactor by pressure, the reaction material at the top of the second reactor overflows into the third reactor, the generated high-concentration calcium formate material gathers at the bottom of the third reactor 130, and water-insoluble impurities float on the top of the third reactor; S2. Remove impurities The synthetic liquid is discharged into a purification kettle, and first heated to 900°C at 101.325 kPa to remove calcium carbonate in the synthetic liquid. Then, after the synthetic liquid is cooled, heavy metal capture microspheres are prepared to precipitate and remove heavy metals in the synthetic liquid. S3, evaporation crystallization The filtered trihydroxy condensation liquid is subjected to multi-stage dehydration by a triple-effect evaporator crystallizer. The triple-effect evaporator removes part of the water in the trihydroxy condensation liquid, the second-effect evaporator concentrates the trihydroxy condensation liquid to a saturated state, and the first-effect evaporator controls the crystallization of calcium formate, so that 80% to 90% of the mass percentage of calcium formate is precipitated and crystallized; S4, centrifugal drying The discharge from the first-effect evaporator is sent to the centrifuge for solid-liquid separation. The liquid enters the sedimentation process, and the crystals are transported to the airflow dryer through the screw feeder. The airflow contacts the crystals and evaporates the water, and then enters the packaging process. S5. Cooling packaging In the packaging process, the crystals are first passed into a cooler for cooling, and then transported to a cooling cyclone separator to reduce the crystal temperature to 40°C and uniformly form product particles for packaging.

2. A calcium formate efficient evaporation and crystallization method according to claim 1, characterized in that: The concentration of the formic acid solution used is 85-95%, the purity of calcium carbonate is greater than 95%, the weight ratio of the formic acid solution added to the first reactor to the calcium carbonate powder is (1.03-1.15):1, the material temperature in each reactor is 30-50°C, and the pH value in each reactor is 3.5-4.

3. A calcium formate efficient evaporation and crystallization method according to claim 1, characterized in that: In step S2, calcium carbonate in the synthetic liquid is removed by heating, and the calcium carbonate is decomposed into calcium oxide and carbon dioxide. The calcium oxide remains in the synthetic liquid and continues to participate in the reaction, while the carbon dioxide escapes.

4. A calcium formate efficient evaporation and crystallization method according to claim 1, characterized in that: In step S3, the triple-effect evaporation crystallizer controls the evaporation rate to 1.5 m / s. 3 / h~2.5m 3 / h, the second-effect evaporator controls the evaporation rate to 2.4m 3 / h, the first-effect evaporator controls the crystallization of calcium formate, so that 85% by mass of calcium formate is precipitated and crystallized.

5. A calcium formate efficient evaporation and crystallization method according to claim 2, characterized in that: Formic acid solution and calcium carbonate powder are added into the first reactor to start the reaction. The reaction material in the first reactor contains unreacted formic acid and calcium carbonate, calcium formate generated by the reaction, water brought in by the formic acid solution and reaction by-product, and impurities brought in by the calcium carbonate powder. The reaction material continues to react while being pressed into the second reactor from the bottom of the first reactor by the liquid level difference. After entering the second reactor, the reaction material flows from bottom to top and overflows from the upper part of the second reactor into the third reactor. The chemical reaction in the third reactor has been basically completed, and the generated high-concentration calcium formate material gathers at the bottom of the third reactor, and water-insoluble impurities float on the upper part of the third reactor.