CS248963B1 - Magnesium oxide and/or its hydratation's products making method - Google Patents

Description

Magnesium oxide and / or its hydration products are produced from magnesite, dolomite or dolomitic limestone, optionally from oxide raw materials, while calcium carbonate is also produced. The carbonates are thermally decomposed. From the obtained roast or mixture of oxides. the calcium oxide is selectively leached at 0 to 100 ° C with a solution containing at least one organic base and at least one salt of an inorganic and / or organic acid with a nitrogen base or bases, in an amount corresponding to the desired degree of leaching of the calcium component. and from the sleeper and / or the oxide feedstock. .

the guinea pigs and the remaining magnesium oxide and / or its hydration products, if any with the non-leached components, are separated from the solution by filtration or centrifugation, generally in conjunction with washing and drying. The leaching solution after the carbon dioxide is removed is recirculated. The method can also be used to refine magnesium oxide from calcium compounds.

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24896

The present invention relates to a process for the production of magnesium oxide and / or its hydration products, including magnesium hydroxide and, as a rule, also calcium carbonate, from predominantly magnesium or calcium-calcium and mainly from carbonate or oxidic raw materials.

Dolomite is the most common rock-forming carbonate after limestone and, due to its chemical composition (30.4% CaO, 21.7% MgO, 47.9% CO2), is an important chemical raw material for the production of magnesium, calcium and oxide compounds. dioxide. Among calcium compounds, extensive use has e.g. calcium carbonate, in particular as a filler, additive or pigment in the plastics, rubber, dye, paper, pharmaceutical, cosmetic, food, chemical, malt and ceramic industries.

Among the magnesium compounds, magnesium oxide is of particular importance as an essential component of basic refractory materials in the steel industry, as well as in the production of fused magnesium oxide for the electrical industry; íahkýcb. and active forms of magnesia, usable in the engineering industry for the treatment of sheet metal surfaces for transformers, in the pulp and paper industry in the so-called. Magnesiumbisulfite pulp production process, in the rubber and plastics industry as an additive to rubber and plastics, in the petroleum processing industry as a catalyst and catalyst carrier, Sorel mortar, in the pharmaceutical industry for the preparation of neutralizers, pastes, powders and the like.

Magnesium oxide and calcium carbonate may be prepared from dolomite or dolomite limestone by partial thermal decomposition to the first stage at a temperature of about 800 ° C, depending on the reaction conditions. However, both compounds exist in the resulting product in the form of a powdery mixture from which they cannot be separated from one another by known physical processes. Among the chemical processes which may be employed are, in particular, the selective leaching of the magnesium oxide with ammonium carboxylate solutions, in particular an aqueous solution of ammonium formate in which the calcium carbonate does not dissolve. Magnesium hydroxide according to U.S. Pat. of the author's certificate no. 180 284, basic magnesium carbonate according to MS. Certificate No. 198 905 or magnesium carbonate trihydrate according to MS. No. 194 644, 208 296. According to MS. by leaching with aqueous solutions of sulphate, nitrate or ammonium chloride, the corresponding magnesium salts are formed, which are further converted to basic carbonate or magnesium oxalate.

These compounds are among the products in the production of magnesium oxide. Other methods of leaching magnesium oxide from limestone doomite are disclosed in Romanian patents 59,712 and 59,779.

Thermal decomposition of dolomite into the second stage at a temperature above 900 ° C results in an oxide mixture containing theoretically 41.7% by weight. MgO and 58.3 wt. CaO. Nor can the two components be separated by physical processes. The method of increasing the content of magnesium oxide in such a prepared product is solved by MS. It is based on the preparation of a suspension of dolomite calcinate, which is treated with nitric acid or ammonium nitrate or ammonium formate or ammonium acetate, and an insoluble residue is separated from the suspension. The calcium salt solutions resulting from the extraction can be treated by simultaneous deposition of ammonia and carbon dioxide to form pure calcium carbonate and the corresponding ammonium salt, thereby achieving recycling of the extractant in the reaction process. In this way, calcium oxide can only be partially removed so that the product formed has a composition in the range of 26.8% CaO and

72.4% MgO to 43.0% CaO and 52.6% MgO based on the annealed condition. However, in addition to the advantages mentioned in the said certificate, the disadvantage of such a process is, on the one hand, only a partial separation of calcium oxide from magnesium oxide and, on the other hand, difficult filterability, washability and dehydration of the product which complicates the manufacturing operations necessary for further processing into a refractory mixture. However, these disadvantages are overcome by the process of the present invention, based mainly on the selective leaching of the calcium oxide and its hydration products from the mixture and the magnesium oxide, its hydration products and possible admixtures, insoluble silicon, aluminum, iron and other starting compounds. dolomite.

According to the present invention, the process for producing magnesium oxide and / or its hydration products from predominantly magnesium and / or predominantly calcium-calcined carbonate and / or oxide feedstocks, optionally in the simultaneous production of calcium carbonate, is effected by thermal decomposition of the feedstock. The calcium oxide obtained is selected selectively by the solution containing at least one organic base and at least one salt and an organic nitrogen base or bases in an amount corresponding to the desired degree of leaching of the calcium constituent from the roast and / or oxide at 0 to 100 ° C. The calcium oxide is selectively precipitated with a solution containing alkylamine and / or alkanolamine and a salt of an organic and / or organic acid with an alkylamine and / or an alkanolamine. Thereafter, the remaining magnesium oxide and / or its hydration products, optionally with unused48963 leached components, are separated from the solution, for example by filtration, centrifugation, generally in conjunction with washing and drying, and after separation into the solution at 10 to 100 ° C at pH 7 to 12, precipitates calcium carbonate which is separated by treatment with carbon dioxide. The leaching solution is carefully used or recirculated.

An advantage of the process according to the invention is the technical simplicity, not requiring a technically overly demanding apparatus, a low number of technological stages of production of relatively pure magnesium oxide and / or its hydration products and, as a rule, simultaneous production of fine-grained calcium carbonate. A further advantage is the possibility of utilizing a wide range of magnesium-lime starting materials, and the method can also be used for purification by other methods of obtaining, produced or commercially available magnesium oxide or its hydration products. It is also an advantage that the production process is generally a closed production cycle in which no harmful gaseous pollutants or pollutants are produced. waste water, since the recovered leaching solution, containing mainly the salt of the nitrogenous base used, returns to the back for careful use in the selective leaching of calcium oxide and / or calcium hydroxide from another fraction of the calcium carbonate raw material. The calcium carbonate produced is of high purity (above 99% by weight of CaCO3j) and contains no other substances which, after its thermal decomposition, would remain in the resulting calcium oxide or in its hydration product.

Magnesium oxide or hydroxide contains only trace amounts of calcium oxide, as well as admixtures of silicon, iron and aluminum compounds originating from the starting dolomite or other magnesium and magnesium salts, respectively. magnesium calcareous raw material.

From the foregoing, it is apparent that the process for producing magnesium oxide and / or its hydration products according to the present invention, wherein the hydration product is a substance or an array of substances resulting from the interaction of water molecules with solid magnesium oxide, is particularly suitable for magnesium. magnesium-calcareous mineral, relatively pure dolomite, dolomitic limestone, magnesia, but also other magnesium and magnesium-calcareous raw materials, mainly in the form of carbonates and oxides. The oxide raw materials according to the invention are considered in addition to magnesium oxide, a mixture of magnesium and calcium oxides, as well as products of their partial or complete hydration. However, the process according to the invention can also be used for refining magnesium oxide and / or magnesium hydroxide, since the product is a much purer oxide or hydroxide. Particularly suitable raw material is magnesia, relatively pure dolomite, or dolomitic limestone, and after some of their initial treatment by thermal decomposition, the calcium oxide formed is obtained, respectively. usually as pure calcium carbonate. Also evident is the synergism of the process according to the invention, which produces rnelen quality magnesium oxide and / or magnesium hydroxide, but generally also magnesium carbonate.

Suitable nitrogen bases are, in particular, the readily available nitrogen bases, such as alkylamines and their derivatives, for example ethylenediamine, piperidine, alkanolamines and derivatives, for example monoethanolamine.n (2-aminoethanol), diethanolamine (HOCH2CH2) 2NH, triethanolamine ( HOCH2CH2) 3N, 1-amino-2-propanol [CH3CH (OH) CH2NH2], 1,3-diamino-2-propanol [H2NCH2C'H (OH) CH2NH2], N, N'-bis- (hydroxyethyl) ethylenediamine ( HOCH2CH2NHCH2) 2, N, NN ', N'-tetrabis (hydroxyethyl) ethylenediamine (HOCH2CH2) 2NCH2CH2N (CH2CH2OH) 2,1,4-di-thiophene} (1,4-dihydroxydiethylpiperazine} HOCH2CH2N (CH2CH2) 2NCH2 other.

In addition to these individual organic nitrogen compounds, mixtures thereof, or systems containing anions of a plurality of inorganic or organic acids, may also be applied, but more preferably, in particular in terms of production stability, only one nitrogen base and its salt are used. Most suitable are nitrogenous organic bases containing at least one carbon atom-bound hydroxyl group and salts thereof, for example monoethanolamine chloride, diethanolamine chloride, monoethanolamine form, and the like.

If the aim of the production process of the present invention is magnesium oxide or its hydration products with a defined or predetermined content of calcium component, for example calcium oxide, then less than the stoichiometric amount of the organic base salt or salts with organic and / or · An inorganic acid corresponding to the desired degree of leaching of the calcium constituent from the sleeper. Where practically complete leaching of the calcium constituent from the bailstock and / or oxide feedstocks is used, a stoichiometric, preferably above-stoichiometric amount of salt or salts of inorganic and / or organic acids with organic nitrogen base or bases in the leaching solution, calculated on leachable content calcium component in the leached feedstock.

The carbon dioxide for frying the calcium carbonate of the present invention can be used both as pure carbon dioxide and in admixture with air, nitrogen, carbon monoxide, methane and other gases that do not react with the leach solution components.

In such cases, when using carbon dioxide-containing gases, this method can additionally be used as a method for concentrating by-gas, e.g. carbon monoxide. Carbon dioxide obtained by thermal decomposition of limestone, dolomite and the like, in particular after separation of the solid particles, can also be used for this purpose.

240963

The leaching aqueous solution of the calcium salt of the appropriate acid (hydrochloric acid, nitric acid, acetic acid, formic acid, etc.) is free from the insoluble magnesium oxide and / or its hydration products and insoluble silicon, iron, manganese and aluminum compounds, present in the starting material, separated by conventional methods, e.g. filtration, blasting.

From the filtrate, by treatment with carbon dioxide at a temperature of 10 to 100 ° C, most preferably at a temperature of 20 to 70 ° C, at a pH of 7 to 12, most preferably at a pH of 7.5 to 9, most preferably at 0.1 to 0.3 MPa, a readily filterable and sedimentable calcium carbonate precipitates which can be separated by conventional methods, e.g. by filtration, decantation, centrifugation and the like.

It is advisable to remove carbon dioxide from the leaching solution used before it is re-used or recirculated by heating, purging with essentially inert gas and the like. A suitable method for removing carbon dioxide from the leaching solution is to bind it by adding calcium oxide or hydroxide. Especially preferred is the use of low-value calcium hydroxide or calcium oxide resulting from various manufacturing processes.

The reaction mechanism for producing magnesium oxide and / or its hydration product, e.g. a mixture of oxides may be represented as follows:

x MgO, Ca CaO-I-2y A. В - MgO Ψ CaA2 4 2B, where

A is a monobasic acid or a mixture of acids,

В is a nitrogen base or a mixture of nitrogen bases,

AB is so! acids or acids with an organic nitrogen base or bases.

By separating (filtering) the undissolved MgO and the admixture from the raw material, a filtrate containing an aqueous solution of CaA 2 and 2B remains. From this, pure СаСОз у CaA2 4- 2yB 4 CO 2 -> уСаСОз-1yA can be precipitated with carbon dioxide. B, which is separated, e.g. filtration, largely regenerating the starting salt A. B. In order to quantitate the precipitation of the calcium component, it is advantageous to have the base V in a slight excess above the stoichiometric amount corresponding to composition A. B.

The process according to the invention can be carried out semi-continuously, continuously and intermittently.

Further details of the process as well as other advantages of the examples are apparent.

Example 1

100 parts by weight, parts of dolomite having a composition of 30.81% by weight. CaO, 21.333 wt. MgO,

0.32 wt. SiO2, 0.21 wt. Al 2 O 3, 0.22 wt. Fe 2 O 3, a loss on ignition of 47.10 percent by mass, is thermally decomposed at 950 degrees Celsius. Dolomite sleeper, ground and sieved through a 0.06 mm sieve, is added in portions to 600 parts by weight of 20 ° C warm aqueous solution containing 120 parts by weight of diethanolamine formate and 50 parts by weight of monoethanolamine. From the solution heated to about 50 to 60 ° C by reaction heat, the insoluble residue containing predominantly magnesium oxide and its hydration products is separated after one hour of stirring, and the filtrate is precipitated from the filtrate cooled to 30 to 40 ° C with carbon dioxide introduced at pH 8 the calcium carbonate which is filtered off, washed with water and dried. Yield 52 parts by weight of calcium carbonate with a content of 99.6% by weight. CaO (calculated on ignition) corresponds to a 95% yield based on the calcium oxide content of the feedstock. The insoluble residue after washing and drying has a composition of 96.65% by weight. MgO, 0.31 wt. CaO, 1.35 wt. % SiO2, 0.83 wt. AI2O3 (considering the annealed condition).

Example 2

100% by weight, parts of dolomite composition

30.61% wt. CaO, 21.67 wt. MgO, 0.15 wt. % SiO2, 0.02 wt. Al 2 O 3, 0.03 wt. Fe2O3, annealing loss 47.50 percent by weight, is thermally decomposed at 1000 ^° C. The dolomite froth, ground and sieved through a 0.06 mm sieve, is suspended in 300 parts by weight of water and the slurry is added in portions. with stirring, add to 300 parts by weight of a 60 ° C warm aqueous solution containing 150 parts by weight of monoethanolamine acetate and 60 parts by weight of monoethanolamine. After stirring for 1 hour, the insoluble residue, containing predominantly magnesium oxide and its hydration products, was collected by filtration and the filtrate cooled to 30-40 ° C, precipitated calcium carbonate after reaching pH 8, filtered, washed with water and dried. Yield 51.5 wt. Parts of calcium carbonate 99.5 wt.%. СаСОз corresponds to 94% yield based on the calcium oxide content of the feedstock. The insoluble residue after washing and drying has a composition of 97.63 percent by weight. MgO. 0.92 wt. CaO, 0.76 wt. S1O2. 0.19% w / w Al 2 O 3, 0.24 wt. ГеЮз (due to the pricked state).

Example 3

100 parts by weight of parts of dolomite roast having a composition of 58.31% by weight; CaO, 41.25 wt. MgO,

0.32 wt. % SiO2, 0.05 wt. Al2O5, 0.05 wt. ГегОз, prepared by thermal decomposition of dolomite at 1000

After grinding, 248 degrees Celsius is added in portions to 1200 parts by weight, parts of a 20 ° C warm aqueous solution containing 280 parts by weight, parts of piperidine chloride and 30 parts by weight of monoethanolamine, with stirring. After stirring for 1 hour, the solution is heated to approximately 50 ^DEG C. by reaction heat and the insoluble residue containing predominantly magnesium oxide and its hydration products is washed with water and dried. Its composition is 97.69% by weight. MgO, 0.94 wt. CaO, 0.81 wt. % SiO2, 0.22 wt. % Al 2 O 3, 0.25 wt. FežOs (based on annealed condition). Calcium carbonate is precipitated from the filtrate at 30 to 40 ° C by the addition of carbon dioxide after reaching pH 7.5, which is filtered off, washed with demineralized water and dried. Yield 100 parts by weight of calcium carbonate having a content of 99.2% by weight. CaCO 3 corresponds to a yield of 97%, based on the calcium oxide content of the feedstock.

Example 4

100 parts by weight of parts of dolomitic limestone of 78.15% by weight. CaO, 20.25 wt. MgO, 0.30 wt. % SiO2, 0.25 wt. % Al 2 O 3 and 1.05 wt. Fe2O3, prepared by thermal decomposition of dolomite limestone at 1100 ° C, after grinding, is added in portions under constant mixing to 1,300 masses, parts of a 15 ° C warm aqueous solution containing 300 masses, parts of monoethanolamine chloride and 45 masses, diethanolamine. After stirring for one hour, the solution is heated to about 50 ° C by reaction heat and the undissolved residue, consisting predominantly of oxide, magnesium and its hydration product, is washed with water and dried at 150 ° C. Zis

383 is a mixture of oxide and hydrated magnesium oxide with admixtures of calcium hydroxide and hydrated silica, alumina and iron oxide. Such a product can be used either directly or after annealing at a temperature of 600 to 1200 ° C. The chemical composition of the product thus prepared is 92.15% by weight. MgO, 0.55 wt. CaO, 1.25 wt. % SiO2, 1.20% wt. % Al2O3 and 4.85 wt. Fe2O3 (relative to the annealed state). Calcium carbonate is precipitated from the filtrate at 60 DEG-70 DEG C. by the carbon dioxide introduced, which is filtered off, washed with water and dried. Yield 135 parts by weight of calcium carbonate having a content of 99.3% by weight. The CaCO 3 corresponds to a yield of 97% based on the calcium oxide content of the feedstock.

Example 5

100 parts by weight of powdered caustic magnesite calf with a composition of 88.5% by weight; MgO, 7.2 wt. CaO, 3.5 wt. S1O2, 0.4 wt. % Al 2 O 3 and 0.3 wt. Fe2O3 is leached at 30 Ό in 300 parts by weight of a solution containing 30 parts by weight, parts of monoethanolamine formate and 3 parts by weight of monoethanolamine under stirring. After 1 hour, the insoluble solid was filtered off, washed with water and dried. The CaO content in the dry matter falls below 0.1% by weight, calculated on the ignited state.

CaCO 3 precipitates from the filtrate with carbon dioxide. Unreacted monoethanolamine carbonate in solution is removed by adding a stoichiometric amount of calcium formate. The solution after separation of the leached CaCO 3, e.g. filtration is used to leach calcium oxide from another fraction of caustic magnesite.

Claims (4)

10 degrees Celsius, after stirring, is added to the stirring portion-wise to 1,200 parts by weight of a 20% warm aqueous solution containing 280% by weight. parts of piperidine chloride and 30 wt. After stirring for 1 hour, the solution is heated to about 50 ° C with a heated reaction heat, and the insoluble residue containing predominantly magnesium oxide and its hydration products is washed with water and dried. Its composition is 97.69% by weight. MgO, 0.94 wt. CaO, 0.81 wt. % SiO2, 0.22% w / w Al2O3, 0.25% w / w. Fe 2 O 5 (with respect to the boiled state). Calcium carbonate precipitates out from the filtrate at a temperature of 7.5 to 40 ° C under a pH of 7.5 and is filtered off, washed with demineralized water and dried. Yield 100%. parts of calcium carbonate having a content of 99.2 wt. The CaCO 3 corresponds to a yield of 97 ° / o, with respect to the oxide content of the calcium feedstock. Example 4 100 wt. parts of a dolomitic sleeper sleeve with a composition of 78.15 wt. CaO, 20.25% by weight; MgO, 0.30 wt. % SiO2.0.25% wt. Al 2 O 3 and 1.05 wt. Fe2O3, prepared by thermal decomposition of dolo-limestone at 1100 [deg.] C., is added to 1,300 wt. 15 ° C of a warm aqueous solution containing 300 wt. monoethanolamine chloride and 45 parts by weight of diethanolamine. After stirring for one hour, the solution is heated to a temperature of about 50 ° C by reaction temperature and the insoluble residue, predominantly of magnesium oxide and the product of hydration, is washed with water and dried at 150 ° C. A mixture of oxide and hydrated magnesium oxide with admixtures of calcium hydroxide and hydrated silica, alumina and ferric oxide is obtained. Such a product can be used either directly or after annealing at 600 to 1200 ° C. The chemical composition of the product thus prepared is 92.15% by weight. MgO, 0.55 wt% CaO, 1.25 wt%. S1O2, 1.20 wt. Al2O3a 4.85 wt. Fe 2 O 3 (with respect to annealing). Calcium carbonate precipitates from the filtrate at 60-70 ° C by carbon dioxide, which is filtered off, washed with water and dried. Yield 135 wt. calcium carbonate content of 99.3 wt. CaCO 3 corresponds to a yield of 97%, based on the calcium oxide content of the feedstock. Example 5 100 wt. parts of powdered magnesite caustic powder with a composition of 88.5% by weight of MgO, 7.2% by weight. CaO, 3.5 wt. % SiO2.0.4% by weight. Al 2 O 3 and 0.3 wt. Fe2O3 continuous carbon black leached at 300 [mu] l in 300 wt. parts of a solution containing 30 wt. parts of monoethanolamine formate and 3 wt. parts of monoethanolamine. After 1 hour, the insoluble solid is filtered off, washed with water and dried. The CaO content in the drier will fall below 0.1% w / w, and the calcined state will be recalculated. CaCO 3 precipitates from the filtrate with carbon dioxide. The unreacted monoethanol amine carbonate in solution is removed by addition of a stoichiometric amount of calcium formate. After separation of the precipitated CaCO3, for example, by filtration, the solution is used to leach the calcium oxide from another portion of magnesite. OBJECT A process for the production of magnesium oxide and / or hydration products thereof, predominantly of magnesium and / or predominantly magnesium-calcium carbonate and / or oxide raw materials, with the simultaneous production of calcium carbonate, characterized in that the starting material in the case of carbon The thermal oxide is thermally decomposed and the calcium oxide obtained from the obtained precipitate and / or oxides is leached selectively at a temperature of 0 to 100 ° C with a solution containing at least one organic base and at least one salt of an inorganic and / or organic acid with organic solvent. with a base or bases, corresponding to the desired degree of leaching of the calcium component from the calcareous and / or oxide raw material and the remaining magnesium oxide and / or its hydration products, optionally with uncoated components, are separated from the solution, for example by filtration, centrifugation , as a rule, by washing and drying. THE INVENTION 2. A process according to claim 1, wherein the calcium oxide is selectively precipitated with an alkylamine and / or alkanolamine, preferably monoethanolamine or diethanolamine salt, and a salt of an inorganic and / or organic acid with an alkylamine and / or an alkanolamine. preferably the hydrochloric acid salt, nitric acid, formic acid or acetic acid, with monoethanolamine or diethanolamine. 3. Process according to clauses 1 and 2, characterized in that after separation of the magnesium oxide and / or its hydration products, the solution is at a temperature of 10 to 100 ° C, preferably at a temperature of 20 to 70 ° C. , at a pH of the solution of 7 to 12, the carbon dioxide is precipitated to give off the calcium carbonate which has gone off. 4. A process according to any one of claims 1 to 3, wherein the leaching solution is preferably used or recirculated, preferably after the removal of carbon dioxide and stealing.