Granted Patent B2

US 12,583,747 · App. 17/791,687 · Granted Mar 24, 2026

Inventors: Peter Stockhoff (Dorsten, DE); Stefan Helmle (Hamm, DE); Deyvi Javier Rivas Villarreal (Dortmund, DE); Nicolai Daheim (Beckum, DE)

Assignees: thyssenkrupp Industrial Solutions AG; thyssenkrupp AG

C01B25/232C01B17/74C01B25/234C01F11/468C04B11/005C01P2004/61C01P2004/62C04B2235/447

Abstract

Claims (26)

1 . A process for producing sulfuric acid and cement clinker, the process comprising:

a) digesting raw phosphate in a first step with concentrated sulfuric acid and converting the raw phosphate to calcium sulfate in a form of dihydrate, hemihydrate, or a combination of hemihydrate and dihydrate, and phosphoric acid;

b) separating off the calcium sulfate as a solid from a liquid phase of a suspension that is obtained;

c) treating the calcium sulfate from step (b), separated off from the phosphoric acid, and/or calcium sulfate/phosphogypsum from a stockpile with an acid to give a suspension with purified calcium sulfate and a P 2 O 5 -containing acid solution;

d) determining a t MIN , wherein t MIN is a time at which an acid concentration during the treatment in step (c) is a minimum, and separating off the purified calcium sulfate after step (c) as a solid from a liquid phase of the suspension that is obtained, wherein the separation of the purified calcium sulfate from the suspension is started at a time in a range from t MIN +30 minutes to t MIN −30 minutes; and

e) mixing the purified calcium sulfate that is separated off and obtained in step (d) with admixtures and reducing agent to give a raw meal mixture for cement clinker production;

f) burning the raw meal mixture to give the cement clinker, with sulfur dioxide being formed as an offgas; and

g) supplying the sulfur dioxide as raw material to sulfuric acid production to produce the sulfuric acid.

2 . The process of claim 1 wherein the separation of the purified calcium sulfate from the suspension in step (d) is started at a time in a range from t 1 +20 minutes to t 1 −20 minutes, wherein t 1 is a time at which the acid concentration during the treatment in step (c) has been reduced by at least 1.0% of an initial acid concentration.

3 . The process of claim 1 wherein the separation of the purified calcium sulfate from the suspension in step (d) is started at a time in a range from t MIN +15 minutes to t MIN −15 minutes.

4 . The process of claim 1 wherein the treatment of the calcium sulfate/phosphogypsum from the stockpile without the calcium sulfate from step (b) is treated in a separate step with an acid and either

a suspension that is formed is supplied to step (d), or

a suspension that is formed is supplied to a separate separating unit and in the separate separating unit a solid is separated from a liquid phase comprising a P 2 O 5 -containing acid solution.

5 . The process of claim 1 wherein the calcium sulfate is separated off from the phosphoric acid in step (b) by filtration.

6 . The process of claim 1 wherein the calcium sulfate in step (c) is either:

from the stockpile, or

obtained from a separating unit of step (b), wherein calcium sulfate filtercake obtained after a first separation from the phosphoric acid is used directly or after one or more washes with liquid.

7 . The process of claim 1 wherein at least one of:

in step (c) the acid is added in an amount such that a weight ratio of solids to liquid in the suspension is in a range from 1/5 to 1/1;

an acid resulting from the treatment in step (c) is a 3 to 10 molar acid;

the acid in step (c) is hydrochloric acid, nitric acid, sulfurous acid, and/or sulfuric acid;

the treatment in step (c) is performed at a temperature in a range from 30 to 80° C.; or

a duration of the treatment in step (c) is in a range from 15 to 90 minutes.

8 . The process of claim 1 wherein a D v (50) of a grain size distribution of calcium sulfate anhydrite obtained in step (d) is in a range of 0.5-100 μm.

9 . The process of claim 1 wherein the purified calcium sulfate from step (d) accounts for more than 70% by weight of a total calcium sulfate in the raw meal mixture.

10 . The process of claim 1 wherein the entire process is performed in a single integrated production plant complex.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (87)