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Method for the preparation of lactic acid and calcium sulphate dihydrate

A technology of calcium sulfate dihydrate and calcium sulfate hemihydrate, which is applied in the direction of carboxylate preparation, carboxylate preparation, separation/purification of carboxylic acid compounds, etc., and can solve problems such as unsuitable dihydrate crystal growth

Inactive Publication Date: 2008-06-18
PURAC BIOCHEM
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this has the disadvantage that the transition from the hemihydrate form to the dihydrate form occurs too early, the conditions under which this transition occurs are not suitable for the growth of dihydrate crystals, and the final calcium sulfate formed still contains significant amounts of phosphate

Method used

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  • Method for the preparation of lactic acid and calcium sulphate dihydrate
  • Method for the preparation of lactic acid and calcium sulphate dihydrate
  • Method for the preparation of lactic acid and calcium sulphate dihydrate

Examples

Experimental program
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Effect test

Embodiment 1

[0021] The solubility of calcium sulfate dihydrate and calcium sulfate hemihydrate was determined at each concentration as a function of temperature. A lactic acid stock solution was prepared by diluting pharmaceutical quality 90% lactic acid aqueous solution (PH90 batch number 200200003) to 20 wt% and 50 wt% respectively with water, and heating at 80° C. for 4 days. 50 ml samples of these solutions were heated at various temperatures for 30 minutes, after which 10 g of calcium sulfate dihydrate or calcium sulfate hemihydrate were added to form a suspension. Samples of 20 ml of this suspension were taken after 15 and 20 minutes and filtered through a G4 glass filter. Analyze mother liquor to determine Ca 2+ content. The filtered calcium sulfate crystals were washed twice with 20 ml of acetone and twice with 10 ml of acetone, and finally dried at 30° C. to remove residual acetone. The water of crystallization content was determined by drying the crystals at 160°C for at leas...

Embodiment 2

[0026]In a 3-liter volume double-wall reaction vessel equipped with a stirrer (stirring speed 600rpm), continuously acidify an aqueous solution containing 34.01% by weight of calcium lactate ( The solution temperature is 95°C; the flow rate is 30.57ml / min), forming more than 95.7% by weight of CaSO 4 0.5H 2 O. The reaction was controlled by measuring the conductivity (min 10.0, max 14.5 mS / cm). The residence time in the reaction vessel was about 75 minutes. The reaction mixture was then fed successively into two 5-liter double-walled crystallization vessels equipped with stirrers (crystallization vessel 1: T=80° C., stirring speed 400 rpm; crystallization vessel 2: T=80° C., stirring speed 400 rpm). The results obtained during the experiments are given in Table 2 below. Table 3 presents the analysis results of the dihydrate crystals obtained after the second step and the aqueous lactic acid solution.

[0027] Table 2 (crystallization vessel 2)

[0028] time (hou...

Embodiment 3

[0032] In a 3-liter volume double-wall reaction vessel equipped with a stirrer (stirring speed 800rpm), continuously acidify an aqueous solution containing 50% by weight of calcium lactate ( Solution temperature is 83-85°C; flow rate 28ml / min), forming more than 97.5% by weight of CaSO 4 0.5H 2 O. The reaction was controlled by measuring the conductivity (min 5.4, max 5.80 mS / cm). The residence time in the reaction vessel was about 62 minutes. The reaction mixture was then fed successively into two 5-liter double-walled crystallization vessels equipped with stirrers (crystallization vessel 1: T=62° C., stirring speed 300 rpm; crystallization vessel 2: T=60° C., stirring speed 300 rpm). The results obtained during the experiment are given in Table 4 below. Table 5 shows the analysis results of the dihydrate crystals obtained after the second crystallization and the aqueous lactic acid solution.

[0033] Table 4 (crystallization vessel 2)

[0034] time (hours)

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Abstract

The invention relates to a method for the preparation of lactic acid and calcium sulphate, in which (a) an aqueous solution that contains lactate is reacted with sulphuric acid at a temperature that is essentially higher than the transition temperature of calcium sulphate dihydrate / calcium sulphate hemihydrate (CaSO<4>.2H<2>O / CaSO<4>.O.5H<2>O), to form a mixture that contains calcium sulphate hemihydrate and lactic acid, (b) the mixture from step (a) is subjected to at least one recrystallisation step at a temperature that is essentially lower than the transition temperature of calcium sulphate dihydrate / calcium sulphate hemihydrate, to form a precipitate of calcium sulphate dihydrate and an aqueous solution of lactic acid, and (c) the precipitate of calcium sulphate dihydrate is separated off from the aqueous solution of lactic acid.

Description

technical field [0001] The invention relates to a preparation method of lactic acid and calcium sulfate dihydrate. Background technique [0002] It is known that (S)-lactic acid can be produced in water by the fermentation of sugars by microorganisms. Usually the pH of the fermentation medium is adjusted by adding calcium hydroxide, with the result that calcium lactate is formed. The concentration of calcium lactate is about 275g calcium lactate per liter or less. In order to be able to recover (S)-lactic acid in the form of acid from the fermentation medium, sulfuric acid (usually in the form of concentrated sulfuric acid) is added to form an aqueous solution of lactic acid and calcium sulfate dihydrate (CaSO 4 2H 2 O), calcium sulfate dihydrate is moderately soluble in water. Calcium sulphate dihydrate is separated by filtration from the aqueous lactic acid solution, after which the aqueous lactic acid solution is subjected to a number of subsequent steps in order to o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C59/08C01F11/46C12P7/56C07C51/02C07C51/41C07C51/42C07C51/43C07C51/44
CPCC01F11/466C07C51/42C01F11/46C07C51/02C07C51/44C07C59/08
Inventor 马库斯·格克玛阿尔德温·科雷沃尔达米安·米歇尔·安德烈·卡默洛扬·范布罗伊吉尔海尔特-扬·威特克安普奥古斯蒂·塞尔达·巴罗
Owner PURAC BIOCHEM
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