A method for manufacturing calcium maleate, calcium cis-epoxysuccinate, or tartaric acid.

Abstract

This invention discloses a method for manufacturing calcium maleate, calcium cis-epoxysuccinate, or tartaric acid. The method for manufacturing calcium maleate includes the following steps: S1, reacting maleic acid with mixed granular calcium carbonate to generate calcium maleate. The mixed granular calcium carbonate comprises 20-50 mm blocky calcium carbonate and 50-300 mesh fine powder calcium carbonate, with a mixing ratio of 30-70%:70-30%. This invention provides a method for manufacturing calcium maleate. This method optimizes the calcium carbonate particle structure, balancing reaction rate and purity control, ensuring efficient oxidation conversion while suppressing metal ion-induced side reactions, ultimately improving the yield of tartaric acid.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and more specifically, to a method for manufacturing calcium maleate, calcium cis-epoxysuccinate, or tartaric acid. Background Technology

[0002] Tartaric acid is a chiral organic acid that exists primarily in three optical isomers: the levorotatory isomer (L-tartaric acid, L(+)-tartaric acid), the dextrorotatory isomer (D-tartaric acid, D(−)-tartaric acid), and the racemic isomer (DL-tartaric acid) formed by an equal mixture of the two. Among these, D-tartaric acid, due to its unique physicochemical properties and optical activity, has significant application value and broad market prospects in various fields such as medicine, food, and chemicals.

[0003] Currently, the industrial synthesis route for D-tartaric acid typically begins with maleic anhydride as the starting material, which undergoes an oxidation reaction to generate a calcium cis-epoxysuccinate intermediate. High-optical-purity D-type products are then obtained through enzymatic catalysis or chemical resolution. The overall process route is as follows:

[0004] maleic anhydride + calcium source (Ca(OH)2 or CaCO3) + H2O2 → cis-calcium epoxy succinate

[0005] cis-epoxysuccinate calcium → via enzymatic conversion → D-tartaric acid

[0006] The formation of calcium maleate is a key step that determines the synthesis efficiency and purity, and currently two main calcium source routes are used:

[0007] (a) Calcium hydroxide method Ca(OH)2

[0008] Calcium hydroxide is a strong base with a fast reaction rate, and can rapidly neutralize the hydrolysis products of maleic anhydride and form a precipitate. However, this method has the following drawbacks:

[0009] 1. The reaction is too violent and may easily trigger side effects;

[0010] 2. Difficulty in pH control may lead to catalyst deactivation;

[0011] 3. Strong alkaline environments may impair the stability of hydrogen peroxide, resulting in decreased oxidation efficiency and higher costs.

[0012] (II) Calcium carbonate method (CaCO3)

[0013] Calcium carbonate reacts mildly, producing CO2 while also buffering pH, maintaining the reaction in a neutral or slightly alkaline range. This makes it suitable for the stability of hydrogen peroxide and catalysts. Its advantages include:

[0014] 1. The reaction is highly controllable, facilitating industrial scale-up;

[0015] 2. It is catalyst-friendly, which helps to improve reaction selectivity;

[0016] 3. Abundant raw materials, low cost, and high safety.

[0017] Therefore, calcium carbonate has gradually become the preferred calcium source in the synthesis of calcium maleate. However, despite its many advantages, this route still faces numerous technical challenges in actual industrial production, especially in terms of raw material purity and impurity control. Currently, natural calcium carbonate with a particle size of 50–120 mesh is mostly used as the reaction raw material, and the synthesis yield of calcium maleate is generally between 93% and 95%, leaving room for improvement. Further process optimization is needed to enhance the overall yield and product quality. Summary of the Invention

[0018] This invention aims to overcome the problem of low yield of calcium maleate in existing technologies and provides a method for manufacturing calcium maleate. This method optimizes the calcium carbonate particle structure, balancing reaction rate and purity control, ensuring efficient oxidative conversion while suppressing metal ion-induced side reactions, ultimately improving the yield of tartaric acid.

[0019] The present invention also proposes a method for manufacturing cis-epoxysuccinate calcium.

[0020] This invention also proposes a method for manufacturing tartaric acid.

[0021] The technical solution adopted in this invention is: to provide a method for manufacturing calcium maleate, comprising the following steps:

[0022] S1. Maleic acid is reacted with mixed granular calcium carbonate to generate calcium maleate. The mixed granular calcium carbonate comprises 20-50 mm block calcium carbonate and 50-300 mesh fine powder calcium carbonate, with a mixing ratio of 30-70%:70-30%.

[0023] Current technologies typically use finely powdered calcium carbonate, which has a fast reaction rate but increases the metal ion concentration. Lump calcium carbonate reacts more slowly.

[0024] The applicant discovered that the use of natural powdered calcium carbonate as a calcium source in the prior art affects the yield of calcium maleate because:

[0025] Despite its large specific surface area, which allows it to react rapidly with maleic acid to form intermediates, its fine particle size and high surface exposure make it more prone to introducing metal impurity ions, such as Fe, during mining and mechanical crushing. 3+ Fe 2+ Al 3+ Mn2+ Mg 2+ Cr 3+ Zn 2+ Cu 2+ The aforementioned metal ions mainly originate from two sources: firstly, from metal oxides or silicate impurities present in natural ores; and secondly, from wear and tear on mechanical equipment such as pulverizers and ball mills during the calcium carbonate crushing process. During the oxidation reaction stage, especially in the presence of H₂O₂ and with the aid of a catalyst, these metal ions readily induce the following side reactions:

[0026] such as Fe 3+ It can catalyze the Fenton reaction, generating hydroxyl radicals (·OH), which accelerate the decomposition of H2O2;

[0027] This may further promote a Clemensen-type cleavage reaction in the main reactant, maleic acid, or its intermediates, initiating chain scission. Clemension byproducts may include:

[0028] Small molecule acids: acetic acid, formic acid, malonic acid;

[0029] Aldehydes: acetaldehyde, formaldehyde.

[0030] These byproducts not only reduce the utilization rate of maleic acid, but also contaminate the mother liquor system, causing excessive impurities in subsequent processes; reduce the selectivity of oxidation conversion; and affect the overall yield and quality of calcium maleate.

[0031] In contrast, lumpy calcium carbonate contains more impurities during its natural mineral formation process, resulting in less release of these impurities, a smaller surface area, and a milder reaction, which effectively reduces the risk of impurity leaching and side reactions. However, its slow reaction rate and large particle size can lead to problems such as prolonged reaction time and incomplete reaction if used alone.

[0032] For the reasons stated above, this application, by using block and powdered calcium carbonate in a specific manner and in a specific ratio, can significantly improve the following problems:

[0033] A. While ensuring a sufficient reaction rate, effectively reduce the content of metal impurities;

[0034] B. To achieve a balance between the stability and reactivity of calcium carbonate under oxidizing conditions;

[0035] C. Control the particle size of blocky calcium carbonate to no more than 50mm to avoid accumulation, deposition, and mass transfer obstacles.

[0036] Therefore, the technical route of "mixed granular calcium carbonate + maleic acid oxidation to synthesize calcium maleate" provided by the present invention can improve reaction yield and selectivity; reduce impurity content and improve the purity of calcium maleate product; reduce post-processing burden and save production costs; and is suitable for large-scale continuous process scale-up, with good industrial application prospects.

[0037] According to one embodiment of the present invention, the surface modification treatment of the blocky calcium carbonate involves coating with one or more of calcium stearate, calcium phosphate, and silane coupling agents, and the coating layer thickness is 1-5 μm; the specific beneficial effects are as follows:

[0038] 1. Surface coating modification of blocky calcium carbonate can effectively remove surface-active impurities or form an inert protective layer, inhibiting the migration and dissolution of impurity metal ions. This is especially effective in systems containing oxidants (such as hydrogen peroxide used in the subsequent preparation of cis-epoxysuccinate calcium), significantly reducing Fe content. 3+ Cu 2+ Mn 2+ Free radical chain side reactions or Fenton reactions initiated by impurity ions can control the non-selective degradation of maleic acid from the source.

[0039] 2. Surface coating treatment is applied to the blocky calcium carbonate. The coating material is calcium stearate, calcium phosphate, or a silane coupling agent. The coating layer thickness is controlled between 1-5 μm. After coating the surface of the blocky calcium carbonate with calcium stearate, calcium phosphate, or a silane coupling agent, during the reaction with maleic acid to form calcium maleate, these coating materials will affect the reaction rate or degree of reaction of calcium carbonate to a certain extent. In particular, calcium stearate, due to its hydrophobic properties, will significantly slow down the reaction and inhibit the contact between the acidic aqueous phase and the surface of the calcium carbonate particles. Calcium phosphate, as an inorganic coating material, slightly isolates the reaction, but it can partially dissolve in an acidic environment, exposing the surface of calcium carbonate. The effect of the silane coupling agent is slight; if the coating is dense and the functional groups are hydrophobic, it will slightly inhibit the reaction. By controlling the coating layer thickness between 1-5 μm, using coarser-particle calcium carbonate, increasing the reaction temperature (e.g., 50-70℃), and increasing the stirring intensity (e.g., stirring speed of 200-600 rpm), the normal formation of calcium maleate can be maintained. In addition, the coating layer can effectively reduce impurity ions (such as Fe). 3+ Cu 2+ Mn 2+ The precipitation of calcium stearate is achieved by preventing the reaction solution from penetrating into grain boundaries or micropores through hydrophobic barrier properties, while calcium phosphate forms an insoluble layer to slow down permeation. Silane coupling agents can form a dense organic-inorganic hybrid film and achieve impurity adsorption or complexation under specific functional group conditions. Therefore, it is recommended to use calcium stearate and an appropriate amount of silane coupling agent (such as KH550) for synergistic coating, with the coating thickness controlled at 1-3 μm. During the reaction, a temperature of 50-70℃ and strong stirring conditions should be used to compensate for the decrease in reaction rate.

[0040] According to one embodiment of the present invention, the mixed granular calcium carbonate is added using a dynamic gradient dosing method:

[0041] (11) Adding 100% fine calcium carbonate in the initial stage of the reaction can quickly neutralize maleic acid due to its small particle size, large specific surface area and high reactivity, effectively increasing the initial reaction rate, shortening the reaction induction period and enhancing the reaction kinetics of the system.

[0042] (12) Add a mixture of 50% lumpy calcium carbonate and 50% fine powder calcium carbonate during the middle stage of the reaction;

[0043] (13) Add 100% lumpy calcium carbonate in the later stage of the reaction and gradually introduce lumpy calcium carbonate in the middle and later stages. In particular, the use of 100% lumpy calcium carbonate in the later stage of the reaction can significantly reduce the release of impurity metal ions in natural calcium carbonate.

[0044] According to one embodiment of the present invention, step S1 further includes a purification step: adding oxalic acid solution or EDTA solution to selectively precipitate metal impurities. By introducing oxalic acid or EDTA solution as a metal ion scavenger, the overall performance of the present invention in controlling side reactions, increasing yield, and ensuring product purity is further improved.

[0045] According to one embodiment of the present invention, a 0.05-0.2 mol / L oxalic acid solution is added, and the mixture is stirred for 20-40 minutes at pH 3-4 and 20-30°C; or

[0046] Add 0.05–0.2 mol / L EDTA solution and stir for 10–60 minutes at pH 4–7 and 25–60°C.

[0047] After the formation of calcium maleate, the introduction of oxalic acid or EDTA solution can selectively complex or precipitate impurity metal ions dissolved in the system, thereby improving product purity and suppressing side reactions. EDTA (diethylenetriaminepentaacetic acid) complexes metal ions through tetradentate or hexadentate coordination to form stable soluble complexes, particularly effective for Fe... 3+ Cu 2+ Mn 2+ EDTA possesses extremely strong complexing ability and can significantly reduce the concentration of free metals under mild conditions; EDTA has a strong effect on Ca... 2+ Its complexing ability is weak and it will not interfere with the formation of calcium maleate. Oxalic acid (H2C2O4) can react with Fe... 3+ Cu 2+ Mn 2+ The formation of insoluble oxalate precipitates allows for efficient impurity removal; however, it can also react with Ca... 2+The reaction produces calcium oxalate precipitate, therefore adding it after the formation of calcium maleate has little impact. During oxalate treatment, if free Ca2+ is present in the system... 2+ At higher concentrations, trace amounts of calcium oxalate byproducts may also be generated. Overall, EDTA is suitable for free calcium... 2+ For systems where precipitation is undesirable or excessive, oxalic acid is suitable for rapid impurity removal and allows for small amounts of precipitate. Both contribute to improving the purity of the final calcium epoxysuccinate and tartaric acid products, suppressing side reactions or catalytic decompositions initiated by metal ions, and significantly improving yield and selectivity, especially in subsequent oxidation and asymmetric synthesis.

[0048] According to one embodiment of the present invention, the mixed granular calcium carbonate is composed of 60% block calcium carbonate, 30% medium-fine powder calcium carbonate (50-120 mesh), and 10% ultrafine powder calcium carbonate (200-300 mesh). This design balances reaction rate and metal ion control. The block calcium carbonate has high purity and stable release, effectively suppressing side reactions. The medium-fine powder increases the initial reaction rate, and the particle size gradient structure optimizes mass transfer efficiency, preventing agglomeration and sedimentation, and improving slurry stability. Combined with a dynamic dosing strategy, it adapts to the entire reaction process, thereby significantly improving the selectivity and yield of calcium maleate to cis-epoxysuccinate, and has good industrial application value.

[0049] A method for manufacturing cis-epoxysuccinate calcium includes the following steps:

[0050] S2. In the presence of a catalyst, calcium maleate is oxidized with peroxide to obtain calcium cis-epoxysuccinate from any of the above-described calcium maleate.

[0051] According to one embodiment of the present invention, the catalyst in step S2 is sodium tungstate and / or sodium molybdate.

[0052] A method for producing tartaric acid includes the following steps:

[0053] (1) Cis-epoxysuccinate calcium is prepared by the manufacturing method of the above-described cis-epoxysuccinate calcium;

[0054] (2) D-tartaric acid or L-tartaric acid is obtained by separating the cis-epoxysuccinate calcium by hand-directed catalysis.

[0055] According to one embodiment of the present invention, the chiral resolution technique is selected from crystallization resolution, enzymatic resolution, or chromatographic separation. Detailed Implementation

[0056] This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application. Of course, they are merely examples and are not intended to limit this application. Furthermore, reference numerals and / or letters may be repeated in different instances. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0057] Unless otherwise specified, all percentages, fractions, and ratios are calculated based on the total mass of the compositions of this application. Unless otherwise specified, all masses of the listed ingredients are given as the content of the active substance and therefore do not include solvents or byproducts that may be present in commercially available materials. The term "percentage by mass" may be expressed by the symbol "%".

[0058] Unless otherwise stated, a singular term may include a plural term and should not be understood as having a quantity of one.

[0059] The terms "preferred," "more preferably," etc., used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application.

[0060] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0061] In the implementation, maleic acid, also known as maleic acid, has the chemical characteristics of having a pair of conjugated carboxyl groups and a cis carbon-carbon double bond. It is easy to undergo a neutralization reaction with alkaline substances to form salts, such as calcium maleate, which is also known as calcium maleate or calcium maleate.

[0062] cis-epoxy calcium succinate, also known as cis-epoxy calcium maleate salt, is a product obtained by epoxidation of calcium maleate. It has a stable lactone-like epoxy structure and strong reactivity, and can be used to further synthesize tartaric acid.

[0063] This embodiment discloses a method for manufacturing cis-epoxysuccinate calcium, comprising the following steps:

[0064] S1. Maleic acid is reacted with mixed granular calcium carbonate to produce calcium maleate. The mixed granular calcium carbonate comprises blocky calcium carbonate with a particle size of 20-50 mm and fine powder calcium carbonate with a particle size of 50-300 mesh, and the two are mixed in a ratio of 30-70%:70-30%. This composite particle size calcium carbonate system is designed to balance reaction rate and control of metal impurities. Fine powder calcium carbonate has the advantages of large specific surface area and high reaction rate, which can effectively promote the initial neutralization process of maleic acid; while blocky calcium carbonate has a lower reaction rate, its slow dissolution helps to stably supply carbonate ions in subsequent reaction stages, while inhibiting the dissolution of metal impurities caused by rapid reaction.

[0065] To further optimize the performance of bulk calcium carbonate, it undergoes pretreatment, specifically surface coating modification. The coating material is one or more of calcium stearate, calcium phosphate, and silane coupling agents. Its function is to form a dense hydrophobic layer or complex protective layer, slowing down the direct contact rate between inorganic acid and the surface of calcium carbonate particles, thereby achieving controllability of the reaction process. The thickness of the coating layer is controlled within the range of 1-5 μm, which maintains the overall reactivity of calcium carbonate while preventing metallic impurities, such as iron, aluminum, and manganese ions, from migrating into the solution phase.

[0066] In this reaction step, the mixed granular calcium carbonate is added using a dynamic gradient method to optimize reaction kinetics. Specifically, this includes: initially adding 100% fine powder calcium carbonate at once, which has a small particle size and high reactivity, rapidly reacting with maleic acid to form calcium salt, significantly increasing the initial reaction rate and shortening the induction period; as the reaction progresses, in the middle stage, a mixture of 50% fine powder and 50% lumpy calcium carbonate is added, i.e., the mixing ratio is 1:1, to balance reaction rate and impurity control; in the later stage of the reaction, only lumpy calcium carbonate is added to ensure a stable carbon source supply in the later stages of the reaction, while controlling the reaction temperature and impurity levels in the system.

[0067] After the formation of calcium maleate, a certain amount of metal impurity ions may still remain in the resulting solution. These ions originate from trace impurities in the calcium carbonate raw material. If not controlled, they will affect the purity of subsequent products and the stability of the process. To achieve selective removal of these metal impurities, oxalic acid solution or EDTA solution is added to the calcium maleate solution to reduce the Fe content in the system. 3+ Al 3+ Mn 2+ Metal ions form stable precipitates or complexes, thereby achieving selective removal.

[0068] Preferably, the concentration of the EDTA solution is controlled within the range of 0.05–0.2 mol / L to balance complexation efficiency and economy. The pH of the reaction system is adjusted to 4–7 to facilitate the effective complexation or precipitation of the target metal ions. Alternatively...

[0069] Oxalic acid solution was added to the calcium maleate solution, with the concentration controlled within the range of 0.05–0.2 mol / L, and uniform addition was achieved through slow dripping or continuous pumping. Simultaneously, the pH of the reaction solution was adjusted to maintain a weakly acidic condition of 3–4, which is conducive to the reaction of oxalic acid and Fe. 3+ Al 3+ Isovalent metal ions form insoluble oxalate precipitates, Mn 2+ It can form stable complexes with oxalic acid or EDTA, improving separation efficiency. During this stage, the system temperature is maintained at 20–30°C, and thorough stirring is performed. The reaction time is controlled at 20–40 minutes to ensure the complete progress of the precipitation or complexation reaction. After the reaction, the precipitate is removed by standing or solid-liquid separation operations (such as filtration or centrifugation), which effectively reduces the content of metal impurity ions in the system, obtaining a high-purity calcium maleate solution, laying the foundation for subsequent process steps.

[0070] S2. In the presence of a catalyst, the calcium maleate is oxidized to calcium cis-epoxysuccinate by oxidizing with hydrogen peroxide. The catalyst used can be sodium tungstate, sodium molybdate, or a combination of both, and its main function is to activate hydrogen peroxide and increase the selective conversion rate of the reaction intermediate to calcium cis-epoxysuccinate. The oxidant in this reaction system is hydrogen peroxide, the reaction temperature can be controlled between 60-70℃, and the holding time is 2-4 hours.

[0071] In an improved embodiment, the mixed granular calcium carbonate comprises: 60% blocky calcium carbonate, 30% medium-fine powder calcium carbonate with a particle size of 50-120 mesh, and 10% ultrafine powder calcium carbonate with a particle size of 200-300 mesh. Through the synergistic ratio of these three different particle sizes, a balance is achieved between reaction rate, reaction controllability, and impurity control.

[0072] After obtaining calcium maleate, it can be further used in the preparation of cis-epoxysuccinate. Specifically, a certain amount of hydrogen peroxide is added to the above-mentioned cis-epoxysuccinate, and the reaction system temperature is maintained between 60-68℃ for 2-4 hours. Subsequently, the pH of the reaction solution is adjusted to neutral, so that calcium maleate is converted into cis-epoxysuccinate. During this process, in order to further remove residual hydrogen peroxide, heating or adding hydrogen peroxide-decomposing enzymes can be used to ensure that there is no hydrogen peroxide residue in the finished product, which meets the safety requirements of food or pharmaceutical grade products.

[0073] The resulting cis-epoxysuccinate calcium can be used as a raw material to prepare D-tartaric acid or L-tartaric acid. Specifically, high-purity D-tartaric acid or L-tartaric acid is obtained by using chiral resolution techniques such as crystallization resolution, enzymatic resolution, or chromatographic separation.

[0074] Among them, the crystallization separation method introduces chiral amine compounds to form chiral salts, and then uses the differences in solubility or crystal form of the two salts to selectively crystallize, thereby removing one pair of enantiomers and obtaining a high-purity product of the other enantiomer, which is suitable for industrial-scale preparation; the chromatographic method relies on a chiral stationary phase to separate D / L-tartaric acid, with high separation accuracy, and is suitable for the purification of small-scale high-value-added products.

[0075] In this embodiment, enzymatic separation is preferred, with the goal of obtaining D-tartaric acid in a targeted manner. Specifically, the reaction system is cooled to 30°C, and 5 grams of L-CEase (cis-epoxysuccinate hydrolase) are added to the calcium cis-epoxysuccinate. The mixture is stirred at a constant temperature within the range of 30-45°C. The tartaric acid content in the system is monitored, and once it stabilizes and stops increasing, filtration is performed to obtain high-purity D-tartaric acid. Example

[0076] This embodiment discloses a method for manufacturing D-tartaric acid, the steps of which include:

[0077] Weigh 98 g of maleic anhydride and add it to 400 mL of pure water. Dissolve the solution under stirring to obtain an aqueous solution of maleic acid. Heat the solution to 60-65 °C and maintain a constant temperature with stirring to promote the reaction.

[0078] A total of 60 grams of mixed granular calcium carbonate was added to the reaction system in stages using a dynamic gradient addition method. This included fine powder calcium carbonate with a particle size of 50-300 mesh and blocky calcium carbonate with a particle size of 20-50 mm. The addition method and proportions are as follows:

[0079] In the initial stage of the reaction, i.e., 0-15 minutes after the initial reaction: add 20 grams of fine calcium carbonate powder at once, accounting for about 33% of the total calcium carbonate added. Fine calcium carbonate powder has a small particle size and a large specific surface area, and reacts rapidly with maleic acid, which can quickly complete the initial neutralization reaction, significantly increase the initial reaction rate, and shorten the reaction induction period.

[0080] During the mid-reaction phase, from 15 to 40 minutes: slowly add 20 grams of mixed calcium carbonate, consisting of 10 grams of finely powdered calcium carbonate and 10 grams of lumpy calcium carbonate in a 1:1 ratio. This stage maintains the reaction rate while introducing a slow-release carbon source, balancing the system's neutralization rate and controlling product deposition.

[0081] In the later stage of the reaction, from 40 minutes after the reaction to the endpoint: the remaining 20 grams of lumpy calcium carbonate, accounting for approximately 33% of the total calcium carbonate, are gradually added. The lumpy calcium carbonate releases carbonate ions slowly, which helps maintain pH stability, further inhibits the dissolution of metal impurities, and optimizes crystal growth conditions.

[0082] During the gradual addition of calcium carbonate, the reaction was maintained at a constant temperature of 60-65℃ with stirring. After the basic addition of calcium carbonate was completed, 1 gram of sodium tungstate catalyst was added in batches, and 145 ml of a 27.5% hydrogen peroxide solution was added dropwise in batches within the range of 60-68℃, controlling the dropping rate to suppress foaming and prevent local overheating. The system was kept at this temperature for 2-4 hours to complete the oxidative conversion of calcium maleate to calcium cis-epoxysuccinate.

[0083] After the reaction is complete, adjust the pH of the system to neutral (pH=7), then heat to 70-100℃ to completely remove any residual hydrogen peroxide. After confirming that there is no residual hydrogen peroxide, cool the system to about 30℃.

[0084] 5 g of levo-cis-epoxysuccinate hydrolase was added at 30℃, and the enzymatic reaction was carried out while maintaining the temperature within the range of 30-45℃ to obtain D-calcium tartrate. When the tartaric acid content showed to be stable and no longer increasing, the reaction was terminated and solid-liquid separation was performed to obtain D-calcium tartrate precipitate.

[0085] The obtained D-calcium tartrate was added to an appropriate amount of dilute sulfuric acid for acidolysis to produce an aqueous solution of D-tartaric acid. This solution was then subjected to impurity removal treatment via anion exchange column and cation exchange column to remove inorganic impurities such as chloride ions, sulfate ions, calcium ions, iron ions, and aluminum ions. The purified solution was concentrated under reduced pressure and then crystallized at a controlled temperature to obtain high-purity D-tartaric acid crystals, which were finally dried to obtain the final product, D-tartaric acid.

[0086] In this embodiment, the blocky calcium carbonate used has undergone surface coating modification treatment.

[0087] The blocky calcium carbonate particles have a diameter of 20-50 mm, and the pretreatment method involves surface coating with calcium stearate. The specific method is as follows: after cleaning and drying the calcium carbonate particles, they are placed in a coating reaction vessel, and a calcium stearate solution is sprayed into them. The coating is stirred at 60°C for 2 hours to form a uniform and dense coating layer on the surface, with the coating layer thickness controlled at approximately 3 μm.

[0088] The coated calcium carbonate exhibits good dispersibility and reaction controllability, significantly reducing the burst release rate of calcium ions during the reaction, decreasing the precipitation of inorganic impurities, and improving the purity and yield of subsequent calcium tartrate. Example

[0089] This embodiment discloses a method for manufacturing D-tartaric acid, the steps of which include:

[0090] Weigh 98 g of maleic anhydride and dissolve it in 400 mL of pure water by stirring to obtain a maleic acid solution. Slowly add 60 g of mixed-size calcium carbonate, which includes a combination of fine powder calcium carbonate and block calcium carbonate, to this solution. The mixed calcium carbonate is preferably 20-50 mm block calcium carbonate and 50-300 mesh fine powder calcium carbonate, with a mixing ratio of approximately 50:50.

[0091] The reaction system was heated to 60-65℃ and stirred to promote the neutralization reaction between maleic acid and calcium carbonate. Within this temperature range, calcium maleate was gradually formed in the system.

[0092] Subsequently, sodium tungstate catalyst was added to the above reaction system in batches, with a total addition of 1 gram, and each addition was controlled to not exceed 20% of the total amount to maintain a steady increase in the catalyst concentration. The temperature was then raised to 60-68℃, and within this temperature range, 145 ml of 27.5% hydrogen peroxide was added in batches. The hydrogen peroxide was added slowly dropwise to ensure a gentle and stable oxidation process, avoiding excessive foaming or localized overheating caused by rapid decomposition of the hydrogen peroxide.

[0093] After adding hydrogen peroxide, maintain the temperature between 60-68℃ for 2-4 hours to ensure complete oxidation of calcium maleate to calcium cis-epoxysuccinate. Then, adjust the pH of the system to neutral to facilitate subsequent product processing. Further increase the temperature to 70-100℃ and continue stirring to remove any remaining hydrogen peroxide until testing confirms that no hydrogen peroxide remains in the system.

[0094] The system was cooled to approximately 30°C, and 5 g of levorotatory cis-epoxysuccinate hydrolase was added. The reaction temperature was maintained between 30-45°C. Within this temperature range, the enzyme maintains high biological activity, promoting the selective degradation of non-target optical isomers. Tartaric acid content was analyzed by intermittent sampling. When the tartaric acid concentration stabilized and ceased to increase, the enzymatic reaction was terminated, and the precipitate was filtered to obtain crude D-calcium tartrate.

[0095] The crude D-calcium tartrate obtained above was dissolved in excess dilute sulfuric acid, undergoing hydrochloric acid hydrolysis to produce a clear solution of D-tartaric acid. To further improve purity and remove impurities, the clear solution was treated using a combination of anion and cation exchange resin columns to sequentially remove any residual inorganic impurities such as chloride ions, sulfate ions, calcium ions, aluminum ions, and iron ions. The treated clear solution was then concentrated under reduced pressure, followed by crystallization at a controlled temperature to precipitate pure D-tartaric acid, which was finally dried to obtain the final product, D-tartaric acid.

[0096] In other embodiments, the mixing ratio of 0-50 mm block calcium carbonate and 50-300 mesh fine calcium carbonate is 40%:60%, 45%:65%, 60%:40%, or 70%:30%.

[0097] In this embodiment, the blocky calcium carbonate used has undergone surface coating modification treatment.

[0098] The blocky calcium carbonate particles have a diameter of 20-50 mm, and the pretreatment method involves surface coating with calcium stearate. The specific method is as follows: after cleaning and drying the calcium carbonate particles, they are placed in a coating reaction vessel, and a calcium stearate solution is sprayed into them. The coating is stirred at 60°C for 2 hours to form a uniform and dense organosilicon coating layer on the surface, with the coating layer thickness controlled at approximately 3 μm.

[0099] The coated calcium carbonate exhibits good dispersibility and reaction controllability, significantly reducing the burst release rate of calcium ions during the reaction, decreasing the precipitation of inorganic impurities, and improving the purity and yield of subsequent calcium tartrate.

[0100] The difference between this embodiment and Embodiment 1 is that in this embodiment, all 60 grams of mixed granular calcium carbonate are added at once, while in Embodiment 1, the calcium carbonate is added dynamically in a gradient. Example

[0101] Specifically, referring to the corresponding steps in Example 1, after obtaining the crude calcium maleate, metal impurities were removed using EDTA solution. This example differs from Example 1 in that a total of 60 grams of mixed granular calcium carbonate was added in stages using a dynamic gradient addition method. This included fine powder calcium carbonate with a particle size of 50-300 mesh and blocky calcium carbonate with a particle size of 20-50 mm. The addition method and proportion are as follows:

[0102] In the initial stage of the reaction, i.e., 0-15 minutes after the initial reaction begins: add 30 grams of fine calcium carbonate powder at once. Fine calcium carbonate powder has a small particle size and a large specific surface area, and reacts rapidly with maleic acid, which can quickly complete the initial neutralization reaction, significantly increasing the initial reaction rate and shortening the reaction induction period.

[0103] During the mid-reaction phase, from 15 to 40 minutes: slowly add 20 grams of mixed calcium carbonate, consisting of 10 grams of finely powdered calcium carbonate and 10 grams of lumpy calcium carbonate in a 1:1 ratio. This stage maintains the reaction rate while introducing a slow-release carbon source, balancing the system's neutralization rate and controlling product deposition.

[0104] In the later stage of the reaction, from 40 minutes after the reaction to the endpoint: gradually add the remaining 10 grams of lumpy calcium carbonate, accounting for approximately 33% of the total calcium carbonate. The lumpy calcium carbonate releases carbonate ions slowly, which helps maintain pH stability, further inhibits the dissolution of metal impurities, and optimizes crystal growth conditions. Example

[0105] Specifically, referring to the corresponding steps in Example 1, after obtaining crude calcium maleate, the metal impurity removal operation is continued.

[0106] After the reaction was completed, a 0.1 mol / L oxalic acid solution was added to the calcium maleate solution to adjust the pH to 3.5. The reaction temperature was controlled at 25°C and stirred at this constant temperature for 30 minutes. Oxalic acid forms insoluble oxalate precipitates with impurity metal ions such as Fe³⁺, Al³⁺, and Ca²⁺ in the solution, utilizing its selective complexing properties to remove metal impurities.

[0107] After precipitation, the solution is allowed to settle and filtered to remove the precipitate, thus obtaining purified calcium maleate solution. Catalyst and hydrogen peroxide are added successively to obtain calcium cis-epoxysuccinate. After adjusting the pH, hydrolytic enzyme is added to obtain calcium D-tartrate. Subsequent acid hydrolysis, ion exchange, crystallization and drying steps are described in the corresponding process of Example 1, and finally high-purity D-tartaric acid product is obtained. Example

[0108] Specifically, referring to the corresponding steps in Example 1, after obtaining crude calcium maleate, metal impurities were removed using EDTA solution.

[0109] Add 0.1 mol / L ethylenediaminetetraacetic acid (EDTA) solution to the reaction system, adjust the pH to 3.8, control the temperature at 30℃, and stir for 30 minutes to promote the formation of stable complexes between Fe³⁺, Al³⁺ and other metal ions and EDTA, which dissolve in the aqueous phase and effectively reduce the content of residual impurities.

[0110] After the complexation process is completed, the complex is removed to obtain a purified calcium maleate solution. A catalyst and hydrogen peroxide are added successively to obtain calcium cis-epoxysuccinate. After adjusting the pH, hydrolytic enzyme is added to obtain calcium D-tartrate. The subsequent acid hydrolysis, ion exchange, crystallization and drying steps are as described in the corresponding process of Example 1. Finally, high-purity D-tartaric acid product is obtained. Example

[0111] Specifically, refer to the corresponding steps in Example 1, the difference being that the blocky calcium carbonate used in this example has not undergone surface coating modification treatment. Example

[0112] Specifically, refer to the corresponding steps in Example 1, the difference being that the mixed granular calcium carbonate used in this example has a multi-size combination structure.

[0113] The total mass of the mixed granular calcium carbonate is 60 grams, which includes:

[0114] 36 grams (60% of total weight) of lumpy calcium carbonate, with a particle size of 20-50 mm;

[0115] 18 grams (30%) of medium-fine powder calcium carbonate with a particle size of 50-120 mesh;

[0116] 6 grams (10%) of ultrafine calcium carbonate with a particle size of 200-300 mesh.

[0117] The three types of calcium carbonate were added in stages according to a dynamic gradient, as follows:

[0118] In the initial stage of the reaction, i.e. 0-15 minutes after the initial reaction: add all the medium-fine powder calcium carbonate (18 g) and ultrafine powder calcium carbonate (6 g), for a total of 24 g;

[0119] In the middle stage of the reaction, i.e., 15 to 40 minutes: add a mixture of 12 grams of lumpy calcium carbonate and 6 grams of medium-fine powder calcium carbonate;

[0120] In the later stage of the reaction, that is, from 40 minutes after the reaction to the reaction endpoint: add the remaining 24 grams of lumpy calcium carbonate.

[0121] Other operational steps, including catalyst addition, oxidation reaction, enzyme conversion and subsequent purification process, are all described in the corresponding operation in Example 2.

[0122] The final product obtained is D-tartaric acid with high purity and few impurities. Example

[0123] Specifically, refer to the corresponding steps in Example 1. The difference is that the removal of residual hydrogen peroxide in the steps is achieved by using hydrogen peroxide decomposing enzyme treatment to replace the traditional heating and volatilization method, thereby optimizing the reaction process and improving the product yield.

[0124] The specific procedure is as follows: After the hydrogen peroxide oxidation reaction is completed, the system is adjusted to neutral (pH about 7.0) by pH adjustment, cooled to 35°C, and then hydrogen peroxide decomposing enzyme (trade name Catalase, enzyme activity of 5000 U / mg) is added to the system. The amount added is about 20 mg of enzyme preparation per 100 mL of reaction solution. The temperature is maintained at 30°C and the reaction is stirred for 30 minutes.

[0125] Hydrogen peroxide decomposable enzymes can efficiently catalyze the decomposition of H2O2 into water and oxygen, removing residual peroxides in the system under mild conditions. This avoids heat loss and unnecessary side reactions caused by high-temperature evaporation, thus protecting the structural stability of cis-epoxysuccinate calcium. Compared with the hydrogen peroxide removal method using heating in Example 1, this method can improve the final yield of cis-epoxysuccinate calcium.

[0126] Subsequent cooling, enzyme conversion, precipitation filtration, acid hydrolysis, purification, and crystallization drying operations were all performed according to Example 1, ultimately yielding high-purity D-tartaric acid.

[0127] Comparative Example 1

[0128] This comparative example is used to compare with Example 1, the difference being that the calcium carbonate used is fine powder calcium carbonate with a single particle size.

[0129] Specifically, 98 g of maleic anhydride was dissolved in 400 mL of pure water, and 60 g of medium-fine powder calcium carbonate with a particle size of 50-120 mesh was added. The mixture was stirred and reacted at 60-65°C. 1 g of sodium tungstate and 145 mL of 27.5% hydrogen peroxide were added in batches as in Example 1. The temperature was maintained between 60-68°C for 2 hours. The pH was then adjusted to neutral, and the residual hydrogen peroxide was removed by heating. The mixture was then cooled, enzymatically converted, and further processed.

[0130] The results showed that the reaction started quickly and the pH dropped rapidly. However, due to the small particle size of calcium carbonate, the pH was difficult to maintain in the middle and later stages of the reaction, resulting in violent fluctuations and local over-acidity of the system, which affected the stability of the reaction and the crystallization process of the product.

[0131] Comparative Example 2

[0132] This comparative example is used to compare with Example 1, the difference being that the calcium carbonate used is fine powder calcium carbonate with a single particle size.

[0133] Specifically, 98 g of maleic anhydride was dissolved in 400 mL of pure water, and 60 g of ultrafine calcium carbonate with a particle size of 200-300 mesh was added. The mixture was stirred and reacted at 60-65°C. 1 g of sodium tungstate and 145 mL of 27.5% hydrogen peroxide were added in batches as in Example 1. The temperature was maintained between 60-68°C for 2 hours. The pH was then adjusted to neutral, and the residual hydrogen peroxide was removed by heating. The mixture was then cooled, enzymatically converted, and further processed.

[0134] The results showed that the reaction started quickly and the pH dropped rapidly. However, due to the small particle size of calcium carbonate, the pH was difficult to maintain in the middle and later stages of the reaction, resulting in violent fluctuations and local over-acidity of the system, which affected the stability of the reaction and the crystallization process of the product.

[0135] Comparative Example 3

[0136] The difference between this comparative example and Example 1 is that the calcium carbonate used is blocky calcium carbonate with a particle size of 20-50 mm, and no surface modification was performed.

[0137] Specifically, dissolve 98 g of maleic anhydride in 400 mL of pure water, add 60 g of lumpy calcium carbonate, and heat the mixture at 60-65°C. Add 1 g of sodium tungstate and 145 mL of hydrogen peroxide in portions, maintaining the reaction temperature at 60-68°C. Because calcium carbonate reacts slowly, the overall reaction time needs to be extended to 5 hours to ensure that the maleic acid reacts completely.

[0138] Experimental results show that the pH of the reaction system is difficult to decrease in the initial stage, the induction period is long, the oxidation effect of hydrogen peroxide is limited, the reaction kinetics are poor, resulting in delayed formation of calcium maleate and precipitation of more insoluble impurities, which affects the purity of the product.

[0139] Comparative Example 4

[0140] The calcium carbonate used in this comparative example consisted of 30g of fine powder calcium carbonate with a particle size of 50-300 mesh and 30g of block calcium carbonate with a particle size of 20-50 mm. The difference from Example 1 was the method of addition.

[0141] Specifically, 98 g of maleic anhydride was dissolved in 400 mL of pure water to obtain a maleic acid solution. 30 g of lumpy calcium carbonate was added, and the mixture was heated at 60-65°C for 50 minutes. Then, 30 g of finely powdered calcium carbonate was added. At the reaction endpoint, 1 g of sodium tungstate and 145 mL of hydrogen peroxide were added in portions, maintaining the reaction temperature at 60-68°C. The initial reaction of calcium maleate was slow and incomplete, forming coarse precipitates. Later, the release of CO2 was vigorous, indicating an unstable reaction.

[0142] To verify the effectiveness of the method of the present invention, the yields and by-reaction products of the products obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were determined and the control effects of metal impurities on side reactions in each group of experiments were compared and analyzed.

[0143] I. Calculation method for product yield:

[0144] The yield calculation for D-tartaric acid preparation from maleic acid must be based on a stoichiometric ratio (1:1 molar ratio). The theoretical maximum yield is the mass of maleic acid input multiplied by the molar mass ratio of tartaric acid to maleic acid (150.09 / 116.07). The actual yield is the percentage of the actual mass of D-tartaric acid obtained relative to the theoretical yield.

[0145] Based on the theoretical conversion yield of maleic anhydride, the mass of the final obtained D-tartaric acid was determined, and the synthesis yield was calculated according to the following formula:

[0146] Yield (%) = (Theoretical maximum mass of D-tartaric acid / Actual mass of D-tartaric acid obtained) × 100%

[0147] Each experiment was repeated three times, and the average value was taken.

[0148] II. Analysis of Side Reactions and Influence of Metal Impurities:

[0149] During the reaction, residual metallic impurities in the system (such as Fe³⁺, Al³⁺, Cu²⁺, etc.) may induce side reactions such as Clemens reduction, transesterification, or complex precipitation, generating insoluble particles or brown or yellow impurities. If these impurities are not removed in time, they will interfere with the nucleation and growth process of tartaric acid crystals, affecting purity and stability.

[0150] In this invention, metal impurities in the system are selectively removed by oxalic acid complexation precipitation (Example 4) and EDTA complexation (Example 5). Combined with anion and cation exchange column treatment, the impurity content in the final product is significantly reduced. GC-MS and ICP-MS analysis confirm that the side reaction products are effectively eliminated and have no significant impact on the purity of D-tartaric acid.

[0151] III. Comparison of Yield and Effect:

[0152] The experimental results are shown in the table below:

[0153] The data above show that although Comparative Examples 1 and 2 had relatively fast reaction rates, the rapid reaction of fine calcium carbonate with maleic acid easily led to local pH anomalies and rapid dissolution of metal ions, resulting in significant side reactions and low yields. Comparative Example 3 used lumpy calcium carbonate, which had a low specific surface area, resulting in a slow initial reaction rate, excessive calcium carbonate residue, incomplete overall reaction, and an even lower yield. Comparative Example 4 initially used lumpy calcium carbonate followed by fine calcium carbonate. The initial use of large-particle calcium carbonate resulted in an unbroken surface coating, leading to an extremely low reaction rate and difficulty in quickly adjusting the pH. Maleic acid persisted in the acidic state, promoting the growth of Fe... 3+ Mn 2+ Impurity ions dissolve in the early stages. When fine powder is added later, the reaction proceeds suddenly and violently, releasing a large amount of foam and causing system disorder. Impurities are difficult to effectively complex or precipitate, affecting the yield and purity of subsequent products.

[0154] In contrast, Example 1 introduces mixed-size calcium carbonate with dynamic gradient dosing. Dynamic gradient dosing achieves gradual pH control: in the initial stage of the reaction, fine calcium carbonate powder has high reactivity, rapidly reacting with maleic acid and neutralizing the acidity, forming a stable reaction starting point; in the middle stage, mixed particle sizes enhance the reaction transition buffer between particles; and in the later stage, larger particles slowly release Ca... 2+ It also extends the reaction time, effectively inhibiting the dissolution of impurity ions and controlling the reaction rate.

[0155] Example 2 involved adding a mixture of granular calcium carbonate in a single wash. Adding all the calcium carbonate particle sizes at once resulted in a rapid reaction and release of CO2 from the fine powder, causing severe foaming and localized overheating. Meanwhile, the larger particles, whose surface coating remained intact, exhibited low reaction efficiency. pH control was disrupted, and residual maleic acid readily formed complexes with impurity ions, leading to a high rate of metal ion precipitation. This significantly increased side reactions in subsequent oxidation steps, negatively impacting the final tartaric acid quality.

[0156] Example 3 uses the same addition method as Example 1, but the ratio of lumpy calcium carbonate to fine powder calcium carbonate in the mixed granular calcium carbonate is different. In Example 1, the ratio of lumpy calcium carbonate to fine powder calcium carbonate is 30:30, while in Example 3, the ratio of lumpy calcium carbonate to fine powder calcium carbonate is 20:40.

[0157] Examples 4 and 5 respectively introduce oxalic acid and EDTA for the complexation and precipitation of metal impurities, effectively removing Fe from the system. 3+ Al 3+ The presence of polyvalent cations reduces the formation of byproducts. Oxalic acid, being a weak organic acid, exhibits good complexation and precipitation effects under conditions of pH 3-4 and 20-30℃, without significantly affecting the activity of sodium tungstate or sodium molybdate catalysts in the system, thus making it more suitable for the system of this invention.

[0158] Example 6 did not involve coating the surface of the bulk calcium carbonate, resulting in a lower yield. This is because the exposed surface of the bulk calcium carbonate is directly exposed to the acidic system, and the uncoated surface of the bulk calcium carbonate easily releases impurity ions (such as Fe). 3+ Cu 2+ Mn 2+ In the reaction system, it forms complexes or deposits in the product crystals, which in turn affects the crystal integrity and purity of calcium maleate, resulting in a decrease in the efficiency of subsequent epoxidation conversion and ultimately a decrease in the overall yield.

[0159] Example 7 achieves a high degree of coupling between particle size structure and reaction kinetics by combining calcium carbonate of different particle sizes and dynamic addition, thus balancing reaction stability and conversion efficiency.

[0160] Example 8 uses hydrogen peroxide enzyme instead of traditional heating decomposition in the hydrogen peroxide removal process to decompose H2O2 under mild conditions, avoiding thermal oxidation side reactions, and further improving the yield and purity of the target product D-tartaric acid, making it the most efficient solution in the current process.

[0161] In summary, the synthesis yield of D-tartaric acid in Examples 1 to 8 of this invention is generally improved compared to Comparative Examples 1-4. Comparing Example 1 with Examples 2 and 6, and Comparative Examples 1 or 2, Example 1, by employing mixed-size calcium carbonate and a dynamic gradient addition method, along with surface coating modification of the bulk calcium carbonate, achieves a synergistic effect. This ensures the reaction rate while inhibiting the dissolution of metal impurities and improving the stability of the intermediate product calcium maleate, thereby significantly increasing the synthesis yield of the final product D-tartaric acid, demonstrating excellent process optimization.

[0162] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0163] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0164] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for manufacturing calcium maleate, characterized in that, Includes the following steps: S1. Maleic acid is reacted with mixed granular calcium carbonate to produce calcium maleate, wherein the mixed granular calcium carbonate comprises 20-50 mm block calcium carbonate and 50-300 mesh fine powder calcium carbonate, and the mixing ratio is 30-70%:70-30%; The blocky calcium carbonate undergoes surface coating modification treatment, with calcium stearate as the coating material and a coating layer thickness of 1-5 μm. The mixed granular calcium carbonate is added using a dynamic gradient dosing method: (11) Add 100% fine calcium carbonate powder in the initial stage of the reaction; (12) Add a mixture of 50% lumpy calcium carbonate and 50% fine powder calcium carbonate during the middle stage of the reaction; (13) Add 100% lumpy calcium carbonate in the later stage of the reaction; Step S1 also includes a purification step: adding oxalic acid solution or EDTA solution to selectively precipitate metal impurities.

2. The method for manufacturing calcium maleate according to claim 1, characterized in that: Add 0.05-0.2 mol / L oxalic acid solution and stir for 20-40 minutes at pH 3-4 and 20-30℃. or Add 0.05–0.2 mol / L EDTA solution and stir for 10–60 minutes at pH 4–7 and 25–60°C.

3. The method for manufacturing calcium maleate according to claim 1, characterized in that: The mixed granular calcium carbonate consists of 60% block calcium carbonate, 30% medium-fine powder calcium carbonate (50-120 mesh), and 10% ultrafine powder calcium carbonate (200-300 mesh).

4. A method for manufacturing cis-epoxysuccinate calcium, characterized in that, Includes the following steps: S1. Calcium maleate is prepared using any one of the methods described in claims 1-3; S2. In the presence of a catalyst, calcium maleate is oxidized with hydrogen peroxide to prepare calcium cis-epoxysuccinate.

5. The method for manufacturing cis-epoxysuccinate calcium according to claim 4, characterized in that: The catalyst mentioned in step S2 is sodium tungstate and / or sodium molybdate.

6. A method for producing tartaric acid, characterized in that: Includes the following steps: (1) Prepare cis-epoxysuccinate calcium using the method described in claim 4 or 5; (2) D-tartaric acid or L-tartaric acid is obtained by separating the cis-epoxysuccinate calcium by hand-directed catalysis.

7. The method for producing tartaric acid according to claim 6, characterized in that: The hand-directed catalysis technology is selected from crystallization resolution, enzymatic resolution, or chromatographic separation.