CS243823B1 - A method for producing ferrous fumarate - Google Patents

Abstract

The invention provides a method for producing ferrous fumarate from maleic anhydride and an ferrous salt of an inorganic acid. Maleic anhydride is heated in a mixture with water with stirring, after dissolution, thiourea is added and the resulting solution is left to stand and cool. The precipitated fumaric acid is separated from the mother liquor and washed with water, after which it is stirred into a suspension with water. This suspension is saturated with gaseous ammonia until completely clear. The resulting ammonium fumarate solution is mixed with the prepared ferrous salt solution, the fumarate precipitate is separated, washed with water and dried.

Description

The invention relates to a process for the preparation of ferric fumarate from maleic anhydride and an inorganic acid ferrous salt.

One of the ingredients added to animal feed is ferrous fumarate. This material is produced by rearranging maleic acid to fumaric acid, converting it to an alkali metal salt, and precipitating ferric fumarate with a solution of a suitable ferric salt of an inorganic acid.

The conversion of maleic acid to fumaric acid is carried out according to the prior art by boiling a solution of maleic acid with hydrochloric acid, acyl chlorides or Lewis acids containing halogen anonides.

The yield of ferric fumarate based on maleic acid is between 75 and 79% of theory. The industrial production of this compound is complicated by the formation of a considerable volume of waste waters containing salts of both organic and inorganic acids. Their processing greatly increases the cost of the entire production, with the loss of both the raw materials and the final product.

For alkali metal salts falling off the process of precipitating the alkali metal fumarate solution with the ferrous salt of an inorganic acid, it is not usually practical to use it. Another major drawback of the processes used so far, resulting from aggressive media used in manufacturing, is the need to use corrosion-resistant construction materials such as high-alloy steel. The energy intensity of the existing production processes is also relatively high.

These deficiencies are largely eliminated by the process for producing ferrous fumarate. according to the invention. The proposed process starts from maleic anhydride, which is heated to 50-60 ° C with stirring in a ratio of 1: 4 to 1:10 with stirring.

After dissolution, thiourea is added in an amount of 0.01 to 6% by weight based on the maleic anhydride feed, the resulting solution is allowed to stand and cool for 0.5 to 24 hours. the precipitated fumaric acid is separated from the mother liquor and washed with water and then stirred at a ratio of 1: 1.4 to 1: 3.0 to a suspension of water.

This suspension is saturated with ammonia gas until it becomes clear. The resulting ammonium fumarate solution is admixed at 95-100 ° C in a stoichiometric ratio with the prepared inorganic acid ferrous salt solution, and the mixture is maintained under stirring for 0.2-2 hours at the same temperature.

Subsequently, after cooling to 40 to 50 ° C, the ferrous fumarate precipitate is separated, washed with water and dried. The mother liquor together with the washing water, which is lost during the separation and washing of the fumaric acid, can advantageously be used for hydrolyzing a further batch of maleic anhydride and dissolving the resulting maleic acid without the subsequent addition of thiourea.

the water from the ferrous fumarate wash can further be used to dissolve the ferrous salt. Prior to mixing the ammonium fumarate solution with the inorganic acid ferric salt solution, the addition of a reducing agent such as alkali metal salts derived from dithioniftite, sulfur or thiosulphuric acid, glucose or ascorbic acid may be advantageously used in an amount of 0.08 to 0.5% by weight, based on the dry weight of the reacting components.

Fumaric acid can also be precipitated from the mother liquor leaving the ferrous fumarate by separating the fumaric acid by addition of sulfuric acid to a pH of 4 to 2 and used in the next production cycle after separation and washing. The remaining solution can be further saturated with ammonia gas and air, the iron hydroxide precipitate separated, and a practically pure ammonium sulfate solution can be obtained. The process for producing the ferrous fumarate according to the invention results in an increase in yield while at the same time reducing the production costs associated with energy consumption and the cost of acquiring and maintaining the production equipment, since the equipment can be constructed of conventional steel.

At the same time, the issue of waste is solved in a complex way. First of all, thiourea is completely regenerated as a maleic acid rearrangement to fumaric acid catalyst by forming a closed mother liquor cycle in the first reaction stage.

Also in the final stage, the amount of waste is substantially reduced, by using washing water and fumaric acid, eliminated from the mother liquor leaving at this stage, in the next production cycles iron hydroxide precipitate and ammonium sulfate solution remain as waste but can be used as fertilizers.

The following examples illustrate the practice of the present invention.

He did

499 kg of water was charged into a reactor equipped with a stirrer and a heating coil and 105.4 kg of maleic anhydride were added. The mixture was heated to 55 ° C with stirring until complete dissolution of the maleic anhydride accompanied by hydrolysis to raaleinic acid.

3.12 kg of thiourea were added to the solution, and the mixture was stirred until the thiourea was completely dissolved. The solution was allowed to stand for 8 hours while cooling to 25-35 ° C.

The precipitated fumaric acid was suction filtered and washed with 19 kg of water. The wash water was combined with the mother liquor. 286 kg of water was charged to another reactor equipped with a stirrer and reflux condenser and a fumaric acid cake containing about 14% water was added with stirring.

The stirred suspension was saturated with gaseous ammonia until it became completely clear indicating complete conversion of the fumaric acid to the ammonium salt. The temperature rose spontaneously to 98-100 ° C during this reaction.

In another reactor equipped with a stirrer, a heating coil, and a reflux condenser, a solution was prepared by heating a mixture of 278.8 kg of hydrated ferrous sulfate (FeSO4.71) and 185 kg of water to 95-97 ° C with stirring.

The ammonium fumarate solution prepared above and the mixture were then added to this solution; stirred for 1 hour at 95-100 ° C. The suspension was cooled to 40 ° C and a brick red precipitate of ferrous fumarate was suction filtered and washed with 185 kg of water to remove traces of ammonium sulfate and ammonium fumarate.

The anhydrous ferrous fumarate product was dried in an oven at 105-120 ° C. Its yield was 154.8 kg, i.e. 85% of theory based on the maleic anhydride feed. To the mother liquor separated at 570 kg from the ferrous fumarate precipitate was added 15.8 kg of a 93% sulfuric acid solution.

After stirring, a precipitate of 11 kg of fumaric acid was collected. The remaining solution was saturated with ammonia gas and air, and the resulting 15.5 kg iron hydroxide precipitate was filtered off. A 20% solution of ammonium sulfate in an amount of 550 kg was obtained as the filtrate.

Example 2

The ferrous fumarate was produced as described in Example 1 except that all of the rearrangement mother liquor from the first reaction step was used to dissolve 100.0 kg of maleic anhydride, to the obtained rearrangement fumaric acid was added washed fumaric acid obtained by treating the mother liquor from the second. of the reaction step according to the example lacquer dissolve 278.8 kg of ferrous sulfate 185 kg of washing water after washing the ferrous fumarate cake.

The yield of ferrous fumarate was 148.5 kg, i.e. 93.6% of theorle based on the maleic anhydride feed.

Example 3

Ferrous fumarate was prepared as described in Example 1 except that 0.60 kg of thiourea was added to the maleic acid solution and allowed to stand for 24 hours.

0.188 kg was added to the ammonium fumarate solution and 0.233 kg sodium dithionite was added to the ferrous sulfate solution.

The feedstock of the other raw materials was the same as in Example 1. The yield of ferric fumarate was 86.0% of theorle based on the maleic anhydride feed.

Example4

The process described in Example 1 produced ferrous fumarate with the difference that 163.4 kg of FeCl 3 · ZH 2 O dissolved in 251 kg of water was used instead of FeSO 4. Ferrous fumarate was obtained in a yield of 84.8% of theorle based on the maleic anhydride feed.

Example 1 a d 5

The ferrous fumarate was prepared as described in Example 1 except that 2.4 kg of thiourea, i.e. 0.4% by weight, was added to the maleic acid solution. 0.05% by weight of ascorbic acid was added to the ammonium fumarate solution and the ferrous salt solution.

The yield of ferrous fumarate was 84.3% theorle based on the maleic anhydride feed.

Example 6

The ferrous fumarate was produced as described in Example 1 except that 4.8 kg of thiourea, i.e. 0.8% by weight, was added to the maleic acid solution. Another difference is the addition of 0.3% by weight of sodium thosulfate to both ammonium fumarate solution and solution

ferrous sulfate before mixing.

The yield of ferric fumarate was 84.0% of theory based on maleic anhydride feed.

Claims (5)

SUBJECT OF THE INVENTION A process for the preparation of ferric fumarate from maleic anhydride and an inorganic acid ferrous salt, characterized in that the mixture of maleic anhydride and water in a ratio of 1: 4 to 1:10 is heated to 50 to 60 ° C with stirring, after dissolution is added thiourea in water. 0.05 to 6% by weight based on the maleic anhydride feed, the resulting solution is allowed to stand and cool for 0.5 to 24 hours, the precipitated fumaric acid is separated from the mother liquor and washed with water, stirred in a ratio of 1 1.4 The solution is added in stoichiometric ratio to the prepared inorganic acid ferrous salt solution at 95-100 ° C, at which temperature the mixture is stirred for about 3 to about 3.0 with water per suspension which is saturated with gaseous ammonia until complete clarification. After cooling to 40 to 50 ° C, the precipitate of ferrous fumarate is separated, washed with water and dried. 2. The process for producing ferrous fumarate according to claim 1, characterized in that the mother liquor separated from the fumaric acid precipitated together with the water resulting from the fumaric acid washing is used to hydrolyze another batch of maleic anhydride and dissolve the resulting maleic acid without the subsequent addition of thiourea. . 3. A process for producing ferrous fumarate according to claim 1 or 2, characterized in that the water resulting from the washing of ferrous fumarate is used to dissolve the ferrous salt. 4. A process for the production of ferrous fumarate according to claims 1 to 3, characterized in that a reducing agent, such as alkali metal salts derived from dithionic, sulfuric or thiosulphuric acid, glucose or acid, is added before mixing the ammonium fumarate solution with the inorganic acid ferrous salt solution. ascorbic, in an amount of 0.05 to 0.5% by weight, based on the dry weight of the reacting components. 5. A process for producing ferrous fumarate according to any one of claims 1 to 4, characterized in that fumaric acid precipitates from the mother liquor leaving the ferric fumarate by adding sulfuric acid to a pH of 4 to 2, separating and washing, the remaining solution being saturated. with ammonia gas and air and the resulting iron hydroxide precipitate is separated.