METHOD AND PLANT FOR TREATING RAW-MEAL IN A CEMENT CLINKER MANUFACTURING PROCESS

Abstract

CO.sub.2 is produced in a cement clinker line by (i) converting a CaCO.sub.3 comprising raw meal into calcined raw meal and at least CO.sub.2 and/or sintering calcined raw meal in a kiln, there-by obtaining at least cement clinker and optionally CO.sub.2. The CO2 emission of the cement clinker line can be significantly reduced by, dissolving at least a portion of the CO.sub.2 in a first carboxylic acid and/or a first sulfonic acid and reducing the dissolved CO2 electrolytically at a cathode of an electrolytic cell to a second carboxylic acid and/or a second sulfonic acid, wherein the first carboxylic acid and/or first sulfonic acid is used as a protonic aqueous electrolyte.

Claims

1.-15. (canceled)

16. A method configured for operating a cement clinker line, the method comprising at least: converting a CaCO.sub.3 comprising raw meal into calcined raw meal and at least CO.sub.2 and/or sintering calcined raw meal in a kiln, thereby obtaining at least cement clinker and CO.sub.2; separating the CO.sub.2 from the calcined raw meal and/or the clinker, dissolving at least a portion of the CO.sub.2 in a first carboxylic acid and/or a first sulfonic acid and/or liquifying at least a portion of the CO.sub.2; reducing the dissolved and/or liquified CO.sub.2, respectively, electrolytically at a cathode of an electrolytic cell to a second carboxylic acid, wherein the first carboxylic acid and/or first sulfonic acid is used as an electrolyte.

17. The method of claim 16, wherein the first and/or the second carboxylic acids are or comprise methanoic acid (H.sub.2CO.sub.2) and/or ethanoic acid (CH.sub.3COOH) and/or methane sulfonic acid (H.sub.3CSO.sub.2OH) or a mixture thereof.

18. The method of claim 16, wherein the reducing comprises using a piece of or comprising at least one of In, Sn, Tl, Ag, Au, Cd, Mn, Hg, Bi, Pb, Cu and/or doped graphene as cathode.

19. The method of claim 16, wherein the electrolyte is heated at least C. above ambient temperature, wherein {2, 5, 10, 15, 20, 25, 30, 40, 50, 60, 70}.

20. The method of claim 16, further comprising withdrawing at least a portion of the first and second carboxylic acids and/or first and second sulfonic acids from the electrolytic cell.

21. The method of claim 20, further comprising using a first fraction of the withdrawn carboxylic acid and/or sulfonic acid in the dissolving step as solvent.

22. The method of claim 20, wherein the converting includes reacting at least a second fraction of the withdrawn carboxylic acid and/or sulfonic acid with CaCO.sub.3 comprised in the raw meal, thereby converting at least as portion of the raw meal into an intermediate raw meal comprising at least calcium carboxylate and/or calcium sulfonate, respectively.

23. The method of the claim 22, wherein the converting further includes heating the intermediate raw meal at least to the decomposition temperature of the calcium carboxylate and/or calcium sulfonate comprised therein, thereby obtaining at least calcined raw meal and the corresponding aldehyde and/or ketone and/or CO.sub.2.

24. The method of claim 23, wherein at least a portion of the aldehyde and/or ketone and/or CO.sub.2 is withdrawn from the calcined raw meal and in that the calcined raw meal is subsequently sintered to cement clinker.

25. The method of claim 16, wherein the first or second carboxylic acid and/or the sulfonic acid, respectively, is at least one of the acids comprised in a list being formed by methanoic acid (H.sub.2CO.sub.2), ethanoic acid (CH.sub.3COOH), propionic acid (CH.sub.3CH.sub.2CO.sub.2H), butanoic acid (CH.sub.3CH.sub.2CH.sub.2CO.sub.2H), pentanoic acid (CH.sub.3(CH.sub.2).sub.3COOH), hexanoic acid (CH.sub.3(CH.sub.2).sub.4COOH), heptanoic acid (CH.sub.3(CH.sub.2).sub.5COOH), octanoic acid (CH.sub.3(CH.sub.2).sub.6COOH), nonanoic acid (CH.sub.3(CH.sub.2).sub.7COOH), decanoic acid (CH.sub.3(CH.sub.2).sub.8COOH), Oxalic acid (HO2CCO2H), Pyruvic acid (CH.sub.3COCOOH), Glyoxylic acid (OCHCOOH), Glycolic acid (HOCH.sub.2CO.sub.2H) and Methane sulfonic acid (CH.sub.3SO.sub.3H).

26. The method of claim 16, wherein the first carboxylic acid and the second carboxylic acids are the same.

27. The method of claim 16, further comprising withdrawing O.sub.2 from an anode of the electrolytic cell and providing the O.sub.2 to a burner of the kiln and/or using the O.sub.2 as to at least partial replace the secondary air and/or tertiary air.

28. The method of claim 16, wherein the alkali ion concentration of the electrolyte in which the CO.sub.2 is dissolved and/or in the liquified CO.sub.2 is below 0.5 mol/liter.

29. A cement clinker line comprising at least a CO.sub.2-source with a CO.sub.2-outlet, wherein the CO.sub.2-source comprises as least one of a kiln configured to sinter calcined raw meal into cement clinker, a calciner configured to convert raw meal into calcined raw meal, and a fuel combustion unit, wherein the cement clinker line further comprises at least: a CO.sub.2 liquefier and/or a first scrubber having at least a CO.sub.2 inlet being connected to the CO.sub.2-outlet of the CO.sub.2-source, an acid inlet connected to at least one source of a first carboxylic acid and/or a first sulfonic acid and a liquified CO.sub.2-outlet and/or an acid-dissolved CO.sub.2-outlet, an electrolytic cell comprising at least a first fluid chamber with a CO.sub.2 inlet being connected with the liquified CO.sub.2-outlet and/or the acid-dissolved CO.sub.2-outlet of the CO.sub.2 liquefier and/or the first scrubber, respectively, and with a CO.sub.2-depleted acid outlet, and with at least one cathode, a second fluid chamber, wherein the first and second fluid chambers are separated by a proton permeable membrane, a cathode in the cathode chamber and an anode in the anode chamber.

30. The cement clinker line of claim 29, wherein the calciner comprises at least a first reactor and a first heater, and wherein: the first reactor further comprises at least: a reactor volume, a CO.sub.2-depleted acid inlet being connected to the CO.sub.2-depleted acid outlet of the electrolytic cell and being in fluid communication with the reactor volume, a raw meal inlet being in fluid communication with the reactor volume, and an intermediate raw meal outlet, being in fluid communication with the reactor volume, the first heater has an intermediate raw meal inlet being connected to the first reactor's intermediate raw meal outlet, a heating volume in fluid communication with the intermediate raw meal inlet, and a calcined raw meal outlet being in fluid communication with the heating volume, the kiln has at least a calcined raw meal inlet and a clinker outlet, wherein the calcined raw meal inlet is connected to the heater's calcined raw meal outlet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In the following, the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment and with reference to the drawings.

[0072] FIG. 1 shows a diagrammatic representation of a method configured to manufacture calcined raw meal.

[0073] FIG. 2 shows a cement clinker line.

[0074] Generally, the drawings are not to scale. Like elements and components are referred to by like labels and numerals. For the simplicity of illustrations, not all elements and components depicted and labeled in one drawing are necessarily labels in another drawing even if these elements and components appear in such other drawing.

[0075] While various modifications and alternative forms, of implementation of the idea of the invention are within the scope of the invention, specific embodiments thereof are shown by way of example in the drawings and are described below in detail. It should be understood, however, that the drawings and related detailed description are not intended to limit the implementation of the idea of the invention to the particular form disclosed in this application, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION

[0076] The embodiment of a method 100 configured to provide calcined raw meal 103 which may be used in a subsequent optional step to manufacture cement clinker may include step 110 of reacting a raw meal 101, including at least limestone or another CaCO.sub.3-source, with a carboxylic acid (ROOH). The carboxylic acid (ROOH) are represented by reference numeral 108.

[0077] In this optional step 110 at least Ca(RCOO).sub.2 is produced (being symbolized by reference numeral 102) wherein the symbol R represents an organic group, as well referred to as organic rest (see (eq 10) and/or (eq 11)). In other words, reference numeral 102 represents the intermediate raw meal. Further H.sub.2O and CO.sub.2 are produced in optional step 110. The reaction(s) may preferably be performed in a temperature range of 175 to 225 C. In this temperature range water of crystallization remains in the gaseous phase. At least approximately normal pressure (1000 hPa100 hPa) is particularly suited, but other pressures may be used as well. Preferably, the such obtained intermediate product is subsequently separated (e.g. filtered) into its solid components 102, i.e. the intermediate raw meal, and its fluid components H.sub.2O and CO.sub.2. This optional separation (filtering) step is symbolized by box 115. The such obtained intermediate raw meal 102 may subsequently be heated in optional step 120 to thereby decompose the calcium carboxylate and/or calcium methane sulfonate of the intermediate raw meal 102 into CaO being at least a component of the such obtained calcined raw meal 103. Further optional products are an aldehyde and/or ketones which may optionally be separated as indicated by dashed lines to box 128. The formation of CaO can be enhanced if the gaseous products of the decomposition are withdrawn, preferably during the optional converting step (see dashed lines to box 128). Alternatively and/or in addition, the optional step of withdrawing the gaseous products can be performed after the optional converting step, this sequence is depicted in FIG. 1 by box 125. The (preferably such obtained) calcined raw meal 103 may optionally be subjected to sintering being indicated by box 130. The gaseous products of the optional converting step 110 may be separated by condensation, thereby removing preferably at least the aldehyde and/or the ketone from the mixture (see box 128). The remaining mixture may be cooled down below the boiling point of water to condense water in the mixture. The remaining mixture may include CO.sub.2, CO and H.sub.2 and may be used as syngas. Alternatively, it may be burnt to essentially produce CO.sub.2 and H.sub.2O, e.g., in the kiln or as energy source for the first heater or to provide process energy for any other subprocess in a cement clinker plant.

[0078] The method may include producing CO.sub.2 in multiple process steps. At least a portion of the CO.sub.2 released by at least one of these process steps may be collected and electrochemically reduced to a carboxylic acid (108) as symbolized by optional box 140. At least a portion of the (preferably such obtained) carboxylic acid may be used in the reacting step 110 to convert the raw meal (101) into the intermediate raw meal (102).

[0079] It should be noted that any of these steps can be performed independently from each other as the as long as the required starting materials are sourced. But preferably at least two of the steps described above are combined. The sequence of the steps may be altered, but the depicted sequence is preferred. In modern plants, one would favor a continuous process over a batch process, i.e. the steps may be performed at the same time, while the product of an earlier step is preferably continuously provided as starting material to a subsequent step.

[0080] FIG. 2 shows a cement clinker line 200 or more precisely a part thereof. For simplicity, well known optional and as well as non-optional components of these cement clinker lines have been omitted, such as for example, the raw-meal mill, the raw-meal preheater, the kiln 400, the clinker cooler and the exhaust stack, a power plant, to name only a few.

[0081] For simplicity any material stream herein is represented by a connection (an arrow) and said connections represent as well conveying means enabling to provide the stream from the source of the stream to the drain of the stream. Connections for fluids are typically conduits, such as pipes. Connections for solid matter may be conveying belts, screw conveyers, chutes, but as well conduits configured to convey fluidized or dispersed solid matter. The tips of the arrows indicate the conveying direction, i.e., the tip of an arrow points to the drain of the stream being represented by the respective arrow.

[0082] CO.sub.2 being produced in the cement clinker line and/or being provided from an external process (e.g., from a power plant burning carbon based fuels) may be provided as a CO.sub.2 stream from such a CO.sub.2 source 201 and may be dissolved in a first acid and/or water in a mixer 210, which may be considered as a first scrubber 210. The first acid may be at least initially provided from an external source 202 as a starting material and/or may be produced by the cement clinker line 200 as explained herein. Preferred examples of such first acids are carboxylic acids such as formic acid, acetic acid or the like as listed in the section SUMMARY and the appended claims. Alternatively or in addition, the first acid may consist of include at least one sulfonic acid, such as e.g. methane sulfonic acid. Other examples are again provided in the section SUMMARY.

[0083] The mixer 210 has an outlet 218. The outlet 218 of the mixer 210 may provide a stream 219 to a dissolved CO.sub.2-inlet 221 of a cathode chamber 220 of an electrolytic cell. The optional stream 219 is represented by an arrow which as well represents the corresponding connection (i.e. the conveying means). Below, we will not again distinguish between streams and connections, as one implies the other. Both terms represent two aspects of the same technical teaching.

[0084] In the optional cathode chamber, the dissolved CO.sub.2 flow is contacted with an optional cathode 225. Preferably, the dissolved CO.sub.2 flows along the optional cathode 225 or at least along a section of the cathode 225. The cathode 225 may be of or include at least one of In, Sn, Hg, Bi, Pb, Cu and/or doped graphene. N-doped graphed is a preferred doped graphene. At the cathode 225, the dissolved CO.sub.2 is reduced to a second acid. The second acid being produced by the reduction depends on the choice of the cathode 225. Preferably the cathode 225 is a catalyst configured to reduce the CO.sub.2 to a carboxylic acid, preferably the same carboxylic or sulfonic acid as the first acid. In other words, the first acid and the second acid are preferably identical.

[0085] The acid-dissolved CO.sub.2 may thus be depleted, while flowing over the cathode. The flow thus converts into a mixture of the first and the second acid, which may leave the cathode via an optional cathode chamber outlet 228. This mixture can as well be referred to as CO.sub.2-depleted (first) acid. Of course, if the first and second acids are selected to be identical, one cannot chemically distinguish which molecule was already provided to the mixer 210 and which molecule has been produced by reducing dissolved CO.sub.2 (physical methods, however allow to: for example mass spectroscopy could distinguish the molecules by using different carbon isotopes for the different starting materials provided to the mixer).

[0086] The optional reduction in the cathode chamber 220 may preferably take place at slightly elevated temperatures to thermodynamically favor the CO.sub.2 reduction to the second acid over the generation of H.sub.2 (HER, as explained above). Slightly elevated means in this context elevated by a positive value above standard conditions (commonly STP: 273.15 K, 1.000 hPa), preferably, {30, 35, 40, 45, 50, 55, 60, 65, 70}. An upper limit is provided by the boiling temperature of the electrolyte (i.e., the first acid) at the given pressure. The lower limit is given by the freezing temperature of the electrolyte. A preferred range of is about 40 to 80, i.e., 4080, particularly preferred is 5060. This temperature range can be obtained by prewarming the first acid upstream of the cathode chamber 220, e.g., upstream of the mixer 219 as symbolized by a heater 246. The heater 246 may be or include a heat exchanger being provided with heat being recuperated at another part of the cement clinker line 200. An example of such heat recuperation is the use of heat being withdrawn from clinker cooler exhaust gas and/or the heat being removed from the stream 229 leaving the cathode chamber outlet 229 by another optional heat exchanger 247 configured to cool the stream 229. Heater 246 and heat exchanger 247 (cooler 247) may as well be combined into an indirect heat transfer heat exchanger, preferably in a counterflow indirect heat transfer type heat exchanger.

[0087] The optional electrolytic cell 450 may further include an optional anode chamber 230. The optional anode chamber has an anode 233 and may be separated from the cathode chamber by an optional cation (e.g. proton) permeable membrane 455. The anode chamber may serve as cation (proton) source configured to the reduce the dissolved CO.sub.2 at the cathode 225 to the second acid in the cathode chamber 220 (see (eq 2) and (eq 3)). Due to the electric potential between the anode and the cathode, H.sub.2O molecules are split into 2H.sup.+ and O.sup.2. Two O.sup.2 anion are oxidized at the anode into O.sub.2 (see (eq 9)). The O.sub.2 is another secondary product of the cement clinker line and may leave the anode chamber as a stream 239, which may as well include H.sub.2O. The stream 239 may be cooled using a heat exchanger 347 (cooler 347) and separated from the stream in a gas-liquid separator 380. The such obtained H.sub.2O may be cycled and provided to the anode chamber 230, preferably, after being heated by heater 346. Heater 346 may as well be a part of a heat exchanger being sourced by recuperated process heat. The O.sub.2 stream leaving the gas-liquid separator is indicated by reference numeral 389. The O.sub.2 produced at the anode may be used, e.g. to replace combustion air in the kiln 400, e.g. to replace at least in part oxygen being provided as primary air to the burner of the kiln 400, to thereby reduce the amount of N.sub.2 in the exhaust gas of the kiln. This reduction thus decreases the total amount of exhaust gas and at the same time increases the CO.sub.2-concentration on the exhaust gas. The exhaust gas may hence be used as CO.sub.2-source 202. Of course it is preferably dedusted and cooled prior to providing it to the mixer 202. Other purification steps may as well be advantageous.

[0088] As already apparent, the mixture of the first and second acids being withdrawn from the cathode chamber outlet 228 is symbolized by a flow 229. Only for simplicity, we assume the first acid and the second acid to be to be identical, to be e.g., both formic acid or both acetic acid). In case they would be different substances one would have to separate the first and second acid, e.g., by distillation or other means. This optional separation is symbolized by a branching point 240. From the branching point, the first acid may flow back as optional stream 248 to the optional mixer 210. An optional pump may be placed in the stream 248 as well as an optional heater 246. The optional pump 245 may as well be placed in a different place of cement clinker line.

[0089] From the optional branching point 240, the second acid may flow to an optional liquid-gas separator 250 (vulgo filter) as indicated by flow 249. Unintended side products of the electrolysis such as H.sub.2 and CO still being (potentially) in the flow 259 are preferably removed. In case the first and second acids are different, the unintended side products can already be removed at optional branching point 240. The liquid-gas separator's 250 outlet may provide CO and H.sub.2 which are to a certain extend unavoidable side products of the reduction of CO.sub.2 (see (eq 4) and (eq 5)). At least these side products may be oxidized in the kiln and/or a gas turbine to CO.sub.2 and H.sub.2O and/or in a burner providing process heat to a reactor and/or used to produce syngas and/or for any other purpose. The heat being released by oxidizing the CO.sub.2 and H.sub.2O may be used, e.g. in the optional heater 246 to reheat the optional stream 248 of the first acid prior to providing it to the optional cathode chamber 220.

[0090] The fluid constituent is the optionally intended aqueous second acid, symbolized as optional stream 259, for example a formic acid stream and/or an acetic acid stream. In an embodiment this second acid may be withdrawn fully or in part from the process and used for any other suited purpose as indicated by optional stream 268. In another embodiment, which may be combined with the embodiment described in the previous sentence as represented by optional branching point 260, at least a portion of the second acid may be provided as optional stream 269 to an optional first reactor 270 and may be reacted therein with raw meal including at least CaCO.sub.3 or consisting of CaCO.sub.3.

[0091] In this optional first reactor 270, the Calcium (Ca) salt of the second acid may be formed, as well as CO.sub.2 and H.sub.2O. The Ca salt is the main ingredient of the intermediate raw meal, as explained in the section SUMMARY. The reactions taking place in the optional first reactor are essentially those of (eq 10) and/or (eq 11). The corresponding method step is herein referred to as reacting step. The temperature in the optional first reactor 270 is preferably be controlled to be above the boiling point of water, to thereby ensure that the water of crystallization is gaseous and can be separated from the solid. The obtained optional gas stream 278 may include essentially CO.sub.2 and H.sub.2O(g) and may be provided to an optional gas separator 280, e.g. via another optional heat exchanger 285. The H.sub.2O may preferably be removed from the optional stream 278 and may be used for other purposes 420 as indicated by optional stream 288. CO.sub.2 can be separated for example by simply condensing the H.sub.2O, although a portion of the CO.sub.2 is likely to be dissolved in the H.sub.2O, depending on the temperature. CO.sub.2 can be withdrawn as gaseous optional stream 289 from the optional gas separator 280 and may be provided to the optional mixer 210. Summarizing, one may say that a portion of the carbon atoms may in an embodiment hence be held in a cycle formed essentially by the optional mixer 201, the optional cathode chamber 220 and the optional first reactor 270. Another portion of the carbon atoms may preferably be removed from the cement clinker line 200 as an aldehyde or ketone: This can be obtained by withdrawing the Ca-salt obtained in the optional first reactor 270 from the optional first reactor 270 (by optional stream 279). Preferably, this stream 279 may be heated as indicated by an optional heater 295 and may be provided to an optional first heater 290. In this optional first heater 290, the Ca-salt may be decomposed into at least one of an aldehyde, a ketone, CO.sub.2, H.sub.2O and CaO. The reactions in this first heater 290 can be summarized by (eqs 12) and/or (eqs 13) and the corresponding method step is herein referred to as converting step or as well as heating step.

[0092] The CaO being produced in the optional first heater 290 is the main component of so called calcined raw meal and may be provided to a kiln 400 configured to sinter it with other starting materials (such as for example clay) to cement clinker. The other components of the raw meal may be included in the starting material being provided initially by a raw meal/CaCO.sub.3 source 201 to the first reactor 270 and/or added to the stream 288 including at least CaO. In the terminology of this application, one may hence say that the raw meal stream 272 being provided to the optional first reactor 270 includes at least CaCO.sub.3 and may optionally include further constituents. The intermediate raw meal stream 279 provided by the first reactor may thus include at least the Ca salt of the second acid and the calcined raw meal stream may include at least CaO.

[0093] In the first heater, the reactions as described by (eqs 12) and/or (eqs 13) take place. At the temperatures present in the first heater 290, only the calcined raw meal at least including CaO is solid, the other products such as CO.sub.2, H.sub.2O, H.sub.2CO or other aldehydes and/or ketones are gaseous and are preferably withdrawn from the optional first heater 290 as indicated by optional stream 299. The stream 299 is preferably cooled down below the condensation temperature of the aldehyde and H.sub.2O as symbolized by the optional heat exchanger 305 (cooler 305). The thereby recuperated heat may be used as process heat in the cement clinker line 200. For example, the optional heat exchanger 305, may be a heat source for the optional heater 356 or any other heater. The still gaseous CO.sub.2 may be withdrawn and merged into stream 278 or by some other route be provided to the optional mixer 210. The aldehyde and ketone and the H.sub.2O in the remaining stream 309 may or may not be separated from each other. The aldehyde and/or ketone is an optional but valuable secondary product of the process. The water maybe used for example as feed water source 204 of the anode chamber 230.

[0094] It will be appreciated to those skilled in the art having the benefit of this disclosure that this invention is believed to provide a method for operating a cement clinker line and a cement clinker line. Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.

LIST OF REFERENCE NUMERALS

[0095] 100 method [0096] 101 raw meal/CaCO.sub.3 [0097] 102 intermediate raw meal [0098] 103 calcined raw meal [0099] 108 carboxylic acid (ROOH) [0100] 110 method step of reacting raw meal 101, (optional) [0101] 115 method step of separating intermediate raw meal and fluid products such as, for example, CO.sub.2 and H.sub.2O, (optional) [0102] 120 step of heating intermediate raw meal 102, (optional) [0103] 125 step of withdrawing the gaseous products, (optional) [0104] 128 method step of separating calcined raw meal and fluid products such as, for example, CO.sub.2 and an aldehyde, (optional). [0105] 130 method step of sintering calcined raw meal, (optional) [0106] 140 method step of electrochemically reducing CO.sub.2, (optional) [0107] 200 cement clinker line [0108] 201 CaCO.sub.3 source/raw meal source [0109] 202 CO.sub.2-source, (optional) [0110] 203 first acid source, (optional) [0111] 218 outlet of mixer/first scrubber 210 providing a stream 219, (optional) [0112] 219 stream of CO.sub.2-being dissolved in water and/or a first acid/conduit 219 connecting outlet 218 of mixer 210 with dissolved-CO.sub.2 inlet 221 of the cathode chamber 220, (optional) [0113] 220 cathode chamber of electrolytic cell 450, (optional) [0114] 221 dissolved CO.sub.2 inlet, (optional) [0115] 225 cathode, (optional) [0116] 228 cathode chamber outlet, (optional) [0117] 229 stream of first and/or second acid, (optional) [0118] 230 anode chamber of electrolytic cell, (optional) [0119] 235 anode, (optional) [0120] 240 (first) branching point, (optional) [0121] 245 pump, (optional) [0122] 247 heat exchanger/heater, (optional) [0123] 248 first acid flow, (optional) [0124] 249 second acid flow, (optional) [0125] 250 gas-liquid separator, (optional) [0126] 258 stream of intended side products, (optional) [0127] 259 stream of second acid, (optional) [0128] 260 (second) branching point, optional [0129] 268 second acid stream, (optional) [0130] 269 second acid stream, (optional) [0131] 270 first reactor, (optional) [0132] 270 stream of CaCO.sub.3 comprising raw meal to the first reactor 270, (optional) [0133] 278 stream of CO.sub.2 and H.sub.2O(g) from the first reactor 270 to first heater 290, (optional) [0134] 280 gas separator, (optional) [0135] 290 first heater, (optional) [0136] 298 CaO comprising calcined raw meal stream, (optional) [0137] 299 stream of gaseous products, (optional) [0138] 295 heater, (optional) [0139] 346 heater/heat exchanger, (optional) [0140] 347 cooler/heat exchanger, (optional) [0141] 380 gas/liquid separator, (optional) [0142] 400 kiln, (optional) [0143] 409 clinker, (optional) [0144] 420 water drain, (optional) [0145] 410 secondary product outlet, (optional) [0146] 450 electrolytic cell, (optional) [0147] 455 membrane, (optional)