Preparation method and equipment of environment-friendly high-efficiency calcium lactate

Abstract

This invention discloses an environmentally friendly and efficient method and equipment for preparing calcium lactate. The specific steps are as follows: Step S1: Using lactic acid and calcium compounds as raw materials, the molar equivalent ratio of the raw materials is controlled to be (2.0-2.1):1; Step S2: During the reaction, humidity is controlled by adjusting the amount of water added to 10%-40% of the total mass of the raw materials; Step S3: The reaction is stirred at 50-85℃ for 1-4 hours to form a calcium lactate slurry; Step S4: The obtained slurry is crystallized at a temperature controlled at 20-40℃; Step S5: The crystallized product is crushed, dried, and pulverized to obtain the finished calcium lactate. This invention can achieve the following energy-saving and environmental protection benefits: no wastewater discharge throughout the process, achieving clean production; energy consumption is reduced by more than 30% compared to traditional methods; no organic solvents are used, reducing environmental pollution; and the raw material utilization rate is high, reducing resource waste.

Description

Technical Field

[0001] This invention belongs to the field of organic calcium salt preparation technology, specifically an environmentally friendly and efficient method and equipment for preparing calcium lactate. Background Technology

[0002] Calcium lactate, an important organic calcium salt, is widely used in the food, pharmaceutical, and chemical industries. Because lactic acid contains an asymmetric carbon atom, it exhibits optical isomers, and its salts also have corresponding optical isomers: L-calcium lactate is levorotatory, and D-calcium lactate is dextrorotatory. According to a US patent, D-lactate ions are somewhat toxic to humans, and the World Health Organization (WHO) has restricted their addition to infant formula, while there are no restrictions on L-lactate.

[0003] The existing technologies for producing calcium lactate mainly include the following methods: 1. Chemical synthesis method: Synthesized using acetaldehyde and hydrogen cyanide as raw materials, this method has high production costs, causes serious environmental pollution, and makes it difficult to synthesize L-lactic acid with a single configuration.

[0004] 2. Fermentation method: L-lactic acid is produced through microbial fermentation. The raw materials are inexpensive and the production process is cleaner. However, the crystallization process is not precisely controlled in current production and the energy consumption is relatively high.

[0005] 3. Neutralization method: This method involves reacting lactic acid with calcium compounds (such as calcium carbonate and calcium hydroxide). However, the traditional method requires excessive water addition, resulting in high energy consumption, inaccurate control of the subsequent crystallization process, and unstable product quality.

[0006] Chinese patent CN104230700A discloses a one-step synthesis process for preparing calcium lactate, using inexpensive and readily available lactic acid and calcium carbonate as raw materials, water as a solvent, and a metathesis reaction to obtain a calcium lactate solution, which is then crystallized by adding ethanol. However, this method uses ethanol as a crystallization medium, which increases the solvent recovery process and costs.

[0007] RS20080297A patent reports the preparation of calcium lactate pentahydrate by reacting lactic acid and calcium oxide in a specific molar ratio (2.08:1 to 2.12:1), but does not precisely control the amount of water added and the crystallization process.

[0008] In summary, the main problems with the existing technology are as follows: 1. Excessive water addition during the reaction process leads to high energy consumption for subsequent evaporation; 2. Inaccurate control of the crystallization process leads to uneven particle size distribution in the product; 3. The use of organic solvents increases costs and environmental burden; 4. Wastewater discharge causes environmental pollution. Summary of the Invention

[0009] The purpose of this invention is to provide an environmentally friendly and efficient method and equipment for preparing calcium lactate, which solves the problems of excessive water addition, high energy consumption, uneven product particle size, and environmental pollution in the prior art.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing environmentally friendly and efficient calcium lactate, the specific steps of which are as follows: Step S1: Using lactic acid and calcium compounds as raw materials, the molar equivalent ratio of the raw materials is controlled so that the molar ratio of calcium ions in lactic acid to calcium compounds is (2.0-2.1):1; Step S2: During the reaction process, humidity is controlled by adjusting the amount of water added to 10%-40% of the total mass of the raw materials; Step S3: Stir and react at a temperature of 50-85℃ for 1-4 hours to form calcium lactate slurry; Step S4: Crystallize the obtained slurry at a temperature controlled between 20-40℃; Step S5: The crystalline product is crushed, dried, and pulverized to obtain the finished calcium lactate product.

[0011] Preferably, the calcium compound in step S1 is one or more of calcium carbonate, calcium hydroxide, or calcium oxide.

[0012] Preferably, the amount of water added in step S2 is 20%-40% of the total mass of the raw materials. More preferably, the amount of water added is 25%-30% of the total mass of the raw materials.

[0013] Preferably, the reaction temperature in step S3 is 65-80℃ and the stirring speed is 200-300 rpm.

[0014] Preferably, a surfactant is added during the reaction in step S3, and the surfactant is sodium dodecylbenzenesulfonate at a concentration of 50-100 mg / kg.

[0015] Preferably, the crystallization process in step S4 employs programmed cooling at a rate of 5-15°C / hour, and seed crystals may be added at a rate of 0.2%-0.3% of the solution mass.

[0016] Preferably, the drying process in step S5 is a segmented drying process: the first stage: drying at 40-60℃ for 1-2 hours to remove free water; the second stage: drying at 70-85℃ for 1-3 hours to reach the required product moisture content. The dried product in step S5 is then crushed and pulverized to obtain the finished calcium lactate product.

[0017] An apparatus for the preparation of environmentally friendly and efficient calcium lactate, comprising: Precision batching device: including water tank, lactic acid storage tank, calcium compound storage tank, weighing scale and water control valve; An integrated reaction and crystallization system connected to a precision batching device includes a stirred reactor, a temperature control system, a vacuum system, and a circulation pump. Solid-liquid separation equipment connected to an integrated reaction crystallization device includes centrifuges or filter presses and conveyor belts. Drying and pulverizing system connected to solid-liquid separation equipment: including crusher, segmented drying equipment and pulverizer; Product packaging systems connected to the drying and pulverizing system include screening equipment and vacuum packaging machines.

[0018] Preferably, the integrated reaction crystallization equipment adopts a jacketed design and is equipped with a precise temperature control device, which can realize programmed cooling and control of the crystallization process.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. Zero wastewater discharge: By precisely controlling the amount of water added, the reaction system achieves water balance, and there is no wastewater discharge throughout the entire process; 2. Reduced energy consumption: Reducing the amount of water added lowers the energy consumption of subsequent evaporation and drying processes, resulting in a reduction of more than 30% in energy consumption compared to traditional methods; 3. Improved product quality: By controlling the crystallization process and adding surfactants, calcium lactate products with uniform particle size can be obtained, with an average particle size of 200-250μm; 4. High process integration: The integrated reaction and crystallization equipment reduces material transfer losses and improves production efficiency. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a schematic diagram of the device of the present invention; In the diagram: 1. Water tank, 2. Lactic acid storage tank, 3. Stone powder feed port, 4. Pump, 5. Mixing tank, 6. Conveyor belt, 7. Low temperature drying room, 8. Crusher, 9. Fluidized bed dryer, 10. Pulverizer. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0022] like Figure 1As shown, an environmentally friendly and efficient method for preparing calcium lactate is described, with the specific process flow as follows: Calculate the feeding ratio → Weigh → Feed (feeding sequence is 1. lactic acid, 2. calcium carbonate, 3. water, water temperature 50~60℃) → Stir (total stirring time controlled within 60 seconds, stirring speed not less than 60 rpm, stirring time after adding water controlled within 10 seconds) → Discharge → Conveyor belt reaction crystallization (conveyor belt length greater than 30 meters, width 2.8 meters, skirt height 20 cm; running speed 0.5 m / min, reaction crystallization time not less than 60 minutes) → Low temperature drying (temperature 40~60℃, conveyor belt drying, time 4~6 hours) → Crushing → High temperature drying (fluidized bed or boiling dry, hot air temperature ≤120℃) → Pulverizing → Packaging and weighing → Sampling and testing → Packaging and warehousing.

[0023] The advantage of choosing calcium carbonate in this invention is that the reaction crystallization process forms a porous state, which facilitates subsequent drying; if calcium hydroxide or calcium oxide is used, it forms a dense state after reaction crystallization, which is not easy to dry, resulting in a long drying time and high energy consumption, with a difference of at least 30%.

[0024] This embodiment also includes equipment for the preparation method of the above-mentioned environmentally friendly and efficient calcium lactate, including a water tank 1 for distributing water, a lactic acid storage tank 2 for supplying lactic acid, a stirring tank 5 for reaction, and a stone powder feeding port 3 for feeding stone powder into the stirring tank 5. The water tank 1 and the lactic acid storage tank 2 are connected to the stirring tank 5 via a pump 4. The discharge end of the stirring tank 5 is connected to a conveyor belt 6, the discharge end of the conveyor belt 6 is connected to a low-temperature drying chamber 7, the discharge end of the low-temperature drying chamber 7 is connected to a crusher 8, the discharge end of the crusher 8 is connected to a fluidized bed dryer 9, the discharge end of the fluidized bed dryer 9 is connected to a pulverizer 10, and the discharge end of the pulverizer 10 is connected to a downstream product packaging system. Example

[0025] Lactic acid and calcium carbonate were used as raw materials in a molar ratio of 2.05:1 (molar ratio of lactic acid to calcium ions). Lactic acid was added to a reaction vessel, and stirring was started. Calcium carbonate powder was slowly added while the amount of water added was controlled to be 30% of the total mass of the raw materials. The reaction temperature was controlled at 70℃, and the reaction time was 2 hours.

[0026] After the reaction was completed, the reaction slurry was transferred to a crystallizer and cooled from 70°C to 25°C at a rate of 10°C / hour. Seed crystals were added at a concentration of 0.25% of the solution mass, along with sodium dodecylbenzenesulfonate as an additive at a concentration of 80 mg / kg.

[0027] After crystallization, calcium lactate crystals are obtained by centrifugation and then dried in stages: the first stage is drying at 50°C for 1.5 hours, and the second stage is drying at 80°C for 2 hours. The dried product is then crushed and pulverized to obtain the finished calcium lactate product.

[0028] The yield of the obtained product reached 87.2%, the purity reached 99.9%, and the average particle size was 236 μm. Example

[0029] Lactic acid and calcium oxide were used as raw materials in a molar ratio of 2.08:1 (molar ratio of lactic acid to calcium ions). Calcium oxide powder was slowly added to a mixture of lactic acid and water, with the amount of water added being 30% of the total mass of the raw materials. The reaction temperature was controlled at 60℃, and the reaction time was 3 hours.

[0030] After the reaction is complete, the reaction slurry is cooled from 60°C to 20°C in a crystallizer at a rate of 8°C / hour. Seed crystals are then added at a concentration of 0.2% of the solution mass.

[0031] After crystallization, calcium lactate crystals were obtained by centrifugation and then dried in stages: the first stage was drying at 55°C for 1 hour, and the second stage was drying at 75°C for 2.5 hours. The dried product was then crushed and pulverized to obtain the finished calcium lactate product.

[0032] The yield of the obtained product reached 85.9%, and the purity was 96.5%. Example

[0033] Lactic acid and calcium hydroxide were used as raw materials in a molar ratio of 2.10:1 (molar ratio of lactic acid to calcium ions). A calcium hydroxide suspension was slowly added to the lactic acid, with water added at 30% of the total mass of the raw materials. The reaction temperature was controlled at 80℃, and the reaction time was 1.5 hours.

[0034] After the reaction was completed, the reaction slurry was cooled from 80°C to 30°C in a crystallizer at a cooling rate of 12°C / hour. Seed crystals were added at a concentration of 0.3% of the solution mass, and sodium dodecylbenzenesulfonate was added as an additive at a concentration of 60 mg / kg.

[0035] After crystallization, calcium lactate crystals were obtained by centrifugation and then dried in stages: the first stage was drying at 45°C for 2 hours, and the second stage was drying at 85°C for 1.5 hours. The dried product was then crushed and pulverized to obtain the finished calcium lactate product.

[0036] The yield of the obtained product reached 86.5%, and the purity was 98.2%.

[0037] Table 1 presents the conclusions obtained by comparing the process conditions of Examples 2-4.

[0038] Process parameters Example 2 Example 3 Example 4 raw material Lactic acid + calcium carbonate Lactic acid + calcium oxide Lactic acid + calcium hydroxide Moor ratio 2.05:1 2.08:1 2.10:1 Water addition amount 30% 30% 30% reaction temperature 70℃ 60℃ 80℃ reaction time 2 hours 3 hours 1.5 hours cooling rate 10℃ / hour 8℃ / hour 12℃ / hour Seed crystal addition amount 0.25% 0.2% 0.3% Product yield 87.2% 85.9% 86.5% Product purity 99.9% 96.5% 98.2% Table 1 Table 1 further validates the advantages of choosing calcium carbonate.

[0039] Key innovations of this invention: 1. Water addition control: By precisely controlling the amount of water added to 20%-40% of the total mass of raw materials, preferably 25%-35%, the optimal fluidity of the reaction system is achieved, while reducing subsequent evaporation energy consumption; 2. Molar equivalent control: Control the molar ratio of lactic acid to calcium ions of calcium compounds to be (2.0-2.1):1 to ensure complete reaction and reduce raw material residue; 3. Crystallization process optimization: By controlling crystal nucleation and growth through programmed cooling and the addition of seed crystals, a product with uniform particle size can be obtained; 4. Surfactant application: By adding surfactants such as sodium dodecylbenzenesulfonate, crystal particle size can be controlled and product performance can be improved; 5. Segmented drying process: Segmented drying avoids overheating and decomposition of the product, ensuring product quality.

[0040] This invention has the following energy-saving and environmental protection benefits: 1. The entire process involves zero wastewater discharge, achieving clean production; 2. Energy consumption is reduced by more than 30% compared to traditional methods; 3. No organic solvents are used, reducing environmental pollution; 4. High raw material utilization rate, reducing resource waste.

[0041] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing environmentally friendly and efficient calcium lactate, characterized in that: The specific steps are as follows: Step S1: Using lactic acid and calcium compounds as raw materials, the molar equivalent ratio of the raw materials is controlled so that the molar ratio of calcium ions in lactic acid to calcium compounds is (2.0-2.1):1; Step S2: During the reaction process, humidity is controlled by adjusting the amount of water added to 10%-40% of the total mass of the raw materials; Step S3: Stir and react at a temperature of 50-85℃ for 1-4 hours to form calcium lactate slurry; Step S4: Crystallize the obtained slurry at a temperature controlled between 20-40℃; Step S5: The crystalline product is crushed, dried, and pulverized to obtain the finished calcium lactate product.

2. The method and equipment for preparing environmentally friendly and efficient calcium lactate according to claim 1, characterized in that: The calcium compound in step S1 is one or more of calcium carbonate, calcium hydroxide, or calcium oxide.

3. The method and equipment for preparing environmentally friendly and efficient calcium lactate according to claim 1, characterized in that: In step S2, the amount of water added is 20%-40% of the total mass of the raw materials.

4. The method and equipment for preparing environmentally friendly and efficient calcium lactate according to claim 1, characterized in that: In step S3, the reaction temperature is 65-80℃ and the stirring speed is 200-300 rpm.

5. The method and equipment for preparing environmentally friendly and efficient calcium lactate according to claim 1, characterized in that: In step S3, a surfactant is added during the reaction process. The surfactant is sodium dodecylbenzenesulfonate, and the concentration is 50-100 mg / kg.

6. The method and equipment for preparing environmentally friendly and efficient calcium lactate according to claim 1, characterized in that: In step S4, the crystallization process employs programmed cooling at a rate of 5-15°C / hour, and seed crystals may be added at a rate of 0.2%-0.3% of the solution mass.

7. The method and equipment for preparing environmentally friendly and efficient calcium lactate according to claim 6, characterized in that: The drying process in step S5 is carried out in stages: the first stage is at a temperature of 40-60℃ for 1-2 hours to remove free water; the second stage is at a temperature of 70-85℃ for 1-3 hours to reach the required product moisture content.

8. An apparatus for preparing the environmentally friendly and efficient calcium lactate according to any one of claims 1-7, characterized in that: include: Precision batching device: including water tank, lactic acid storage tank, calcium compound storage tank, weighing scale and water control valve; An integrated reaction and crystallization system connected to a precision batching device includes a stirred reactor, a temperature control system, a vacuum system, and a circulation pump. Solid-liquid separation equipment connected to an integrated reaction crystallization device includes centrifuges or filter presses and conveyor belts. Drying and pulverizing system connected to solid-liquid separation equipment: including crusher, segmented drying equipment and pulverizer; Product packaging systems connected to the drying and pulverizing system include screening equipment and vacuum packaging machines.

9. The equipment for the preparation method of environmentally friendly and efficient calcium lactate according to claim 8, characterized in that: The integrated reaction crystallization equipment adopts a jacketed design and is equipped with a precise temperature control device, which can realize programmed cooling and control of the crystallization process.

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