< h1 class= "pgc-h-arrow-right" > preparation of magnesium carbonate</h1>
1.1 Properties of magnesium carbonate and preparation method thereof
1.1.1 Properties of magnesium carbonate
Magnesium carbonate (xMGCO3.yMG(OH)2zH2O) is a white monoclinic crystal or amorphous powder, slightly soluble in water, easily soluble in ammonium solution, chemical reaction with acid and hot water, calcination of high-quality magnesium carbonate precursors can obtain high purity magnesium oxide.
Chemical equation for the reaction of magnesium carbonate with acids:
MgCO3 + 2H+ = Mg2+ + H2O + CO2↑
Chemical equation for the reaction of magnesium carbonate with hot water:
MgCO3 + H2O = Mg(OH)2 + CO2↑
Chemical equation for calcination of magnesium carbonate:
MgCO3 = MgO + CO2↑
1.1.2 Classification and application of magnesium carbonate
Magnesium carbonate has a wide range of applications in the chemical industry, different production principles and production processes to produce magnesium carbonate has different product quality and use, according to the purity of magnesium carbonate composition and use of pharmaceutical magnesium carbonate (heavy magnesium carbonate), food grade basic magnesium carbonate, light magnesium carbonate.
(a) Magnesium carbonate (medicinal)
Pharmaceutical magnesium carbonate is heavy magnesium carbonate (CAS: 13717-00-5), its volume is relatively small, it is easier to be adjusted into powder, in the field of medicine is often used in the preparation of antacid neutralization acid drugs, clinically mostly used for the treatment of stomach diseases and duodenal ulcers. In addition, there are also widely used in some high-grade glass products, magnesium oxide, cosmetics, toothpaste, refractory coatings, etc.
(2) Light magnesium carbonate
Lightweight magnesium carbonate (mangnesium carbonate, light) appearance (Appearance) is a white powder, in the industry is extremely excellent rubber reinforcing agent and filler, while lightweight magnesium carbonate is not easy to burn, the density is relatively low characteristics and is used as a high temperature resistant insulation or fireproof materials, its application almost covers national defense, metallurgy, electronics and other socio-economic fields. However, when it is applied in the electronics industry, it must have good physical properties at the same time, its particle size dispersion should be appropriate, purity, activity should be higher, and the raw material preparation, preparation, and pre-application treatment must be strictly processed, so as to ensure that it is uniformly dispersed in the electronic medium. The last thing that needs to be introduced is the transparent lightweight magnesium carbonate, which can be mixed in white rubber to jump the transparency of rubber products, and strengthen the toughness and wear resistance of rubber products when 10/37.
(3) Food grade basic magnesium carbonate
Food grade basic magnesium carbonate relative molecular mass of 458.81, white loose agglomerate powder, which is mainly used as an additive or modifier in the food industry, so its purity must be guaranteed to ensure food safety, especially in the preparation process of heavy metals iron, lead, manganese, arsenic, palladium and other residues must be less than 1ppm. If magnesium carbonate is added to flour, it can increase the whiteness of the flour and can be regarded as a whitening agent. At the same time, magnesium carbonate can also be used as an alkaline agent for some foods or added to toothpaste, ceramics and other daily chemicals.
1.1.3 Classical preparation method of magnesium carbonate
As mentioned above, magnesium carbonate is more diversified due to its relatively complex raw material source, and the insoluble solid carbon dioxide (CO2) carbonization method, soluble raw material carbonate co-precipitation method and hydrothermal synthesis method are the basic core processes for the preparation of magnesium carbonate crystals. Specifically, there are magnesite carbonization method, dolomite carbonization method, brine soda ash method, brine-carbon method, magnesium sulfate soda ash method, hydroxide continuous carbonization method and cyclic voltammetry.
The following articles will briefly introduce them.
(1) Carbonization method
Electrolyte substances containing chemical elements of different components are dissolved in a solvent so that they exist in the form of ions or electrolytes in a given solvent. To this mixture of solutions to add a certain amount of suitable necessary additives, and then to it into excess carbon dioxide (CO2) gas, the reaction product after the established time of the reaction filter pyrolysis, and then the solid product obtained after pyrolysis dried or calcined, thereby preparing a method of high purity material is called carbonization method. The preparation of magnesium carbonate by carbonization method includes dolomite carbonization method, brine-dolomite (limestone) carbonization method, and magnesite carbonization method.
Dolomite (CarMg (CO,), Dolomite) is a colorless / white magnesium carbonate, calcium carbonate combined tripartite natural mineral resources, if the dolomite contains iron (Fe), manganese (Mn), lead (Pb) and other elements present, the color will be slightly different, dolomite is insoluble in inorganic solvent water, relative molar mass 184.399g / mol, 700C-1100C can be calcined decomposed into magnesium oxide (MgO) and calcium oxide (CaO), When the calcination temperature is greater than 1600C, magnesiumite and a-CaO are generated, which are dense in structure and have extremely high fire resistance.
The dolomite carbonization method is to crush the dolomite to the particle size standard (50-80mm), mix it evenly with anthracite white coal according to the proportion of the process, and put it into the calcination kiln to calcinate the mixture to obtain white cloud ash by 700C-1100C. Calcination process reaction chemistry equation:
MgCO· CaCO3 = MgO· CAO + 2CO2↑
Control the carbon dioxide percentage content (35%-40%) in the calcination kiln, and put the white cloud ash into a digester containing waste magnesium water to digest into a refined emulsion.
Reaction chemistry equations for the digestion process:
MgO· CaO + 2H2O = Mg(OH)2+ Ca(OH)2 kiln gas is purified, dusted, cooled, compressed and carbonated together with fine ash milk for use, and then filtered, thermosynthetic decomposition, re-pressed, blower drying, grinding and crushing, packaging box, and finally prepared a target product of a lightweight magnesium carbonate to be sold.
Carbonization process reaction chemistry equation:
Ca(OH)2 + Mg(OH)2 + 3CO2= Mg(HCO3)2+ CaCO3↓ + H2O
Reaction chemistry equations for pyrolysis processes:
Mg(HCO3)2 + 2H2O = MgCO·3HO↓ + CO2↑
Calcination process reaction chemistry equation:
5MgCO·3H2O = 4MgCO· Mg(OH)·4H2O + 10H2O +CO2↑
Dolomite carbonization process
Dolomite (Ca · Mg(CO3)2, Dolomite), limestone-brine carbonization method is to calcinate dolomite and limestone, add water to digest into milk ash, and then add it to the brine to produce magnesium hydroxide (Mg(OH)2) precipitation, and then add water emulsification, carbonizer 34C carbonization, solid-liquid separation to obtain heavy magnesium water (magnesium bicarbonate - Mg (HCO)2) and magnesium-containing calcium carbonate, pyrolysis, washing, drying to obtain light magnesium carbonate. This method differs from the introduction of magnesium sulfate or magnesium chloride and the formation of calcium chloride or magnesium carbonate by-products at the same time as the formation of mg(OH)2 precipitation after the digestion of white dolomite, and the white dolomite used in this method can increase the yield of light magnesium carbonate.
Calcination process principle chemical equation:
MgCO· CaCO3 = MgO· CaO + CO2↑
CaCO3 = CaO + CO2↑
MgO.CaO + 2H2O= Mg(OH)2 + Ca(OH)2
MgCl2+ Ca(OH)2 = Mg(OH)2↓ + CaCl2
Mg(OH)2+ Ca(OH)2+ 3CO2= Mg(HCO3)2+ CaCO3↓+H2O
Mg(HCO3)2+ 2H2O = MgCO33H2O + CO2↑
5MgCO·3H2O=4MgCO.Mg(OH).4H20+ 10H2O+CO2↑
Flowchart of dolomite (CaMg(CO3)2, Dolomite) limestone-brine carbonization
Magnesite carbonization method is the use of magnesite ore as raw material, according to 10:1 with anthracite white coal mixed evenly, into the calcination kiln through 800 "C- 100000 calcination decomposition.
Chemical equations for forging and firing process principles:
MgCO3= MgO + CO2↑
After cooling, a certain amount of distilled water is added to digest to obtain magnesium hydroxide emulsion.
Principles of the digestion process Chemical Equation:
MgO + H2O = Mg(OH)2↓
After that, the boredom is transported to the carbonization tower for carbonization, and then dehydrated, filtered, pyrolyzed, and dried to a lightweight magnesium carbonate ready for sale.
Carbonization process principle chemical equation:
Mg(OH)2+ 2CO2=Mg(HCO3)2
Principles of pyrolysis process Chemical equations:
Mg(HCO3)2+ 2H2O=MgCO3·3H2O↓+CO2↑
MgCO3·3H2O=4MgCO3· Mg(OH)·4H2O+1OH2O+CO2↑Magnesite carbonization process flow chart
This method is almost the same as the preparation process of dolomite (Dolomite) carbonization, but the relative calcium content of magnesite is relatively low, eliminating the need to set up a system equipment for recovering magnesium-containing calcium carbonate, and lightweight magnesium carbonate products will be of better quality, and the production of lightweight magnesium carbonate products by this method can be relatively reduced.
(2) Co-precipitation method
Co-precipitation is the process of putting the relevant raw materials of different components into a solvent and mixing them into a homogeneous - solution, adding an appropriate amount of precipitant to the homogeneous mixture so that the target product is precipitated, and then the precipitate is separated by filtration and calcined to a high purity product. Its advantage is that it is easy to prepare a product with small and uniform strength, and the components are directly obtained after mixing into a homogeneous solution, and the process flow is simple.
Brine-carbonate method is one of the typical processes of co-precipitation method, the brine and carbonate are mixed uniformly according to a certain proportion, maintained - constant temperature stirring for 10min, until the precipitation reaction is over, after filtration or centrifugation, drying, crushing to obtain magnesium bicarbonate products.
5Mg2+ +10HCO3 = 4MgCO· Mg(OH)2·4H2O +6CO2↑
(3) Hydrothermal synthesis
Hydrothermal synthesis (solvothermal reaction) refers to the chemical process preparation process carried out under the conditions of - constant temperature (99C- 999C) and pressure (IMPa-999MPa) in a sealed vessel (such as a high-pressure reactor), with swallow distilled water as the reaction solvent, under the conditions of a certain temperature - constant pressure. Among them, hydrothermal precipitation reaction, hydrothermal hydrolysis reaction, hydrothermal crystallization reaction, hydrothermal oxidation (Oxidation) reaction, hydrothermal reduction (Reduction) reaction, and hydrothermal synthesis reaction are collectively referred to as hydrothermal reaction. We all know that the solubility of raw materials in hot water is generally increased, and hydrothermal methods are convenient for preparing products with fewer defects and excellent performance. Hydrothermal methods have many similarities with sedimentation methods to some extent.
(4) Ammonium salt circulation method
Since the 1990s, numerous scholars have published reports on methods for controlling the microstructure of magnesium carbonate. For example, Tian Peng and Ning Guiling of Dalian University of Technology [2" prepare rod/needle, rose and bulk magnesium carbonate for the preparation of hollow nanomaterials in stencilization. Kelil2} uses magnesium bicarbonate (Mg(HCO3)2) as a magnesium source and carbon source, and synthesizes a hollow hierarchical structure of different microstructures "houseof cards" by adding different amounts of sodium hydroxide precipitators. Chen Jiping 123) et al. used magnesium pinnate (Mg(NO3)2) as the magnesium source and potassium carbonate (K2CO3) as the carbon source, and the effects of reaction temperature, pH value, stirring rate and stirring time on the microstructure of magnesium carbonate crystals were studied. Although the relevant scholars have made certain achievements, the existing research process is basically in the primary small test stage of laboratory synthesis, and the preparation process often has serious waste and relatively high cost defects, and will cause a certain pollution of the environment, which is not in line with the low-carbon economy advocated by the state. Up to now, the more mature process in the chemical industry is the ammonium salt recycling method 24, which uses natural solid magnesium source ore to prepare magnesium carbonate, which significantly saves a large amount of precipitant to a certain extent, which can be regarded as a relatively green and low-carbon economic approach, but this method cannot easily control the microscopic morphology of magnesium carbonate crystals.
Ammonium salt recycling method is a method of producing high-quality lightweight magnesium carbonate crystals, which synthesizes lightweight magnesium carbonate crystals from natural solid magnesium source minerals. The pulverized ore 900C is calcined to magnesium oxide, the calcined magnesium oxide is converted, into the ammonium saline aqueous solution to generate soluble magnesium salt (Mg2+) and ammonia (NH3), ammonia is turned into ammonium bicarbonate by carbonizing the furnace, and the soluble magnesium salt and ammonium bicarbonate are mixed to generate magnesium carbonate and ammonium salt (NH*), this process realizes the recycling of by-product ammonium salt, reduces unnecessary waste, and realizes the green chemical economy.
MgCO3 = MgO + CO2↑/ Mg(0H)2 = MgO + CO2↑
MgO + 2NH+= Mg2+ + H2O+ 2NH3↑
NH3+ H2O + CO2 = NH4HCO3
Mg2+ + 2NH4HCO3 + 2H2O =MgCO3· H2O↓ + 2NH4+ +CO2↑
5MgCO3·3H2O=4MgCO3· Mg(OH)2· H2O +10H2O+ CO2↑
Rhombus bitter soil complex decomposition method
The rhombus method requires the acidification of the rhombus soil powder in a sulfuric acid solution, and then the magnesium sulfate (MgSO4) solution is made by filtered water washing, and the magnesium sulfate solution is carried out with sodium carbonate (Na2CO3) solution or aminocarbonate (NH4HCO3) solution for a simple complex decomposition reaction, and finally the magnesium carbonate crystal is prepared by pyrolysis, filtration separation, drying and other processes.
Equation of reaction of acid sulfate hydrolysis:
MgO + H2SO4 = MgSO4+ H2O
Complex decomposition process chemical reaction equation:
MgSO4 + 2NH4HCO3 = Mg(HCO3)2 +(NH4)2SO4
Mg(HCO3)2 + 2H2O = MgCO3·3H2O↓ + CO2↑
Pyrolysis process chemical reaction equation:
5MgCO3·3H2 = 4MgCO· Mg(OH)·4H2O + 1OH2O + CO2↑
1.1.4 The content of the study and its significance
Magnesium element as one of the metal elements recognized as the earth's richest reserves, with the continuous development and utilization of magnesium salt series products, will make great contributions to the global economy and the improvement of the living standards of all mankind. At present, the development of solid magnesium sources stored on the earth has caused environmental pollution and waste of resources, and all regions of the world are paying attention to the development and utilization of liquid magnesium resources. The most scarce thing in the twenty-first century is resources, and how to effectively and efficiently develop and utilize relatively abundant resources is one of the main research directions of countries in the world.
Magnesium carbonate is one of the important inorganic chemical products of magnesium salt series, which not only has a wide range of direct application value, but also is an important magnesium source for the preparation of other magnesium salt series products. Nanomaterials are widely used in today's society, and it is difficult for traditional nanomaterials to control their morphology, size and hollow structure. In order to overcome the single spherical shape of the hollow nanomaterials prepared by spray drying and bubbling method, relevant scholars created a template method to prepare hollow nanomaterials. However, the traditional method of sacrificing templates requires the consumption of a large number of templates, and the cost is relatively high, resulting in a certain waste of resources. Since China's magnesium resources are relatively rich (NO.1) and the price is relatively low, if magnesium carbonate is used instead of traditional templates and sacrificial templates, it will reduce certain production costs.
Taking the wide application of magnesium carbonate in the economy and society and its possible templating application in the preparation of nanomaterials as the entry point, this paper verifies and discusses the mechanism of different reaction conditions on the microstructure of magnesium carbonate crystal morphology, size and other microstructures, and discusses the optimal conditions for the preparation of certain morphological products.
Chapter 2: Applications of Magnesium Carbonate
<h1 class="pgc-h-arrow-right" >2.1 Instructions for use of magnesium carbonate as a drug</h1>
<h1 class="pgc-h-arrow-right" > 2.1.1 Pharmacological effects and dosage of magnesium carbonate</h1>
Magnesium carbonate is an antacid. After oral administration, magnesium chloride and carbon dioxide are generated in the stomach with hydrochloric acid, which play a role in neutralizing stomach acid, which is weaker than magnesium oxide and also has a laxative effect. Oral: 0.5-1 g 3 times daily.
< h1 class="pgc-h-arrow-right" > 2.1.2 Contraindications and adverse reactions of magnesium carbonate</h1>
People with allergy to magnesium carbonate are contraindicated. Adverse reactions: diarrhea, bloating, belching, etc.
<h1 class="pgc-h-arrow-right" > 2.1.3 Indications</h1>
Chronic gastritis, stomach discomfort symptoms related to stomach acid, such as stomach pain, heartburn, etc
<h1 class="pgc-h-arrow-right" > 2.1.4 considerations</h1>
Magnesium carbonate is a national over-the-counter drug. The precautions are unclear. It has a laxative effect; it can produce CO2 gas, and patients with severe ulcer disease should use it with caution. It is forbidden to be compatible with acidic drugs
<h1 class="pgc-h-arrow-right" > 2.1.5 expert reviews</h1>
Magnesium carbonate as an antacid. After oral administration, magnesium chloride and carbon dioxide are generated in the stomach with hydrochloric acid, which play a role in neutralizing stomach acid, which is weaker than magnesium oxide and also has a laxative effect. Adverse effects may include diarrhea, bloating, and belching. It is a national over-the-counter drug and should not be compatible with acidic drugs.
2.2 chewable aluminum magnesium carbonate tablets
2.1.1 Introduction to aluminum magnesium carbonate
English name: Hydrotalcite
CAS number: 12304-65-3
Molecular formula CH24AL2Mg6O23
MW: 603.98
Density: 2.0g/ml1atm
<h1 class= "pgc-h-arrow-right" > 2.1.2 pharmacological effects</h1>
Pharmacological effect aluminum magnesium carbonate trade name Darcy, Haiti, basic aluminum carbonate, is aluminum hydroxide, magnesium hydroxide, carbonate and water compounds, its active ingredient is hydrated magnesium aluminum hydroxide, there is a unique layered network structure, not only can directly neutralize gastric acid, reversible binding pepsin, but also in an acidic environment combined with bile acid, inhibit the activation of lecithin, adsorbed on the surface of the carrier film after chewing can quickly alleviate symptoms. The mild effect of this product can avoid the aggravation of gastric acid secretion caused by excessive pH. In addition, the long-lasting effect is another feature of this product, under the same conditions, the duration of action of this product is 6 times that of sodium bicarbonate. Chewing this product can effectively solve the problem of bile reflux, neutralize stomach acid and pepsin, and eliminate the damaging effect of mixed reflux on the esophageal carrier.
1. Neutralize stomach acid. This product can maintain the pH of gastric juice between 3 and 5, neutralize 99% of gastric acid, inactivate 80% of pepsin, and the antacid effect is rapid, mild and long-lasting.
Protects the gastric mucosa. This product can increase the synthesis of prostaglandin E2 and enhance the gastric mucosal barrier effect. It can also promote the release of epidermal growth factors in the gastric mucosa, increase the content of phospholipids in the hydrophobic layer of the submucus, and prevent gastric mucosal damage caused by H+ reverse osmosis.
3. This product can adsorb and bind pepsin, directly inhibit its activity, and benefit the ulcer surface. The repair can also be combined with bile acids and adsorption of hemolytic phosphatidylcholine, preventing damage to these substances and destroying the gastric mucosa. Animal experiments have shown that this product can inhibit gastric ulcer induced by histamine, bile acid and hydrochloric acid; It also cancels out the adverse reactions of constipation and diarrhea due to the two metal ions contained in this product, aluminum and magnesium.
It is used for acute and chronic gastritis, duodenoccalitis, gastric ulcer, duodenal ulcer, which can alleviate the symptoms of heartburn, acid reflux, nausea, vomiting, bloating and other symptoms caused by excessive stomach acid.
2. For reflux esophagitis and bile reflux.
3. For the prevention of gastric mucosal damage of nonsteroidal drugs.
<h1 class="pgc-h-arrow-right" > 2.1.4 Adverse reactions</h1>
Contraindications To patients with allergy to this drug, hypermagnesemia, achloroid deficiency, colostomy, ileostomy, hypophosphatemia, unexplained gastrointestinal bleeding, appendicitis, ulcerative colitis, diverticulitis, chronic diarrhea, intestinal obstruction are contraindicated.
2. Use with caution in patients with gastrointestinal peristalsis dysfunction, severe cardiac and renal dysfunction, and hypercalcemia.
<h1 class="pgc-h-arrow-right" > 2.1.5 Drug Interactions</h1>
1. This product can affect or interfere with the absorption of anticoagulants, H2 receptor blockers, tetracyclines, goose deoxycholic acid, etc., so the combination of the two must be spaced 1 to 2 small. time.
2. Antacids containing aluminum and magnesium may reduce the absorption of azithromycin, cefpoxime, ceftopramipipil, ketoconazole, azanavir, quinolones, phenothiazines, atenolol, digoxin, chloroquine, isoniazid, ibandronic acid and other drugs, and should be taken at an interval of 1 to 4 hours when combined with these drugs.
3. Antacids containing aluminum and magnesium should be avoided in combination with mycophenolic acid, clofazimine, levothyroxine and other drugs, because the blood concentration of these drugs can be reduced.
4. Antacids can increase the pH value in the stomach, hinder the dissolution of lansoprazole particles, resulting in a decrease in their bioavailability, so the time of taking antacids should be at least 1 hour earlier than lansoprazole. 5. Antacids (especially those containing magnesium) can reduce the bioavailability of misoprostol while increasing the adverse reactions of the latter. Attention should be paid to monitoring for symptoms of diarrhea caused by misoprostol when combined, and in severe cases, antacids should be discontinued and/or reduced in the amount of misoprostol.
6. Magnesium-containing antacids can promote the absorption of glyburide and trigger hypoglycemia, so they should not be combined.
7. Magnesium-containing antacids combined with calcitriol can lead to hypermagnesemia, so they should not be combined.
8. When aluminum-containing antacid drugs are combined with vitamin D3, it can lead to increased absorption of aluminum, increased blood concentration, and cause aluminum poisoning, so it is not appropriate to combine two drugs (especially for those with impaired renal function).
9. The combination of antacids containing aluminum, calcium or magnesium with polysulfonyl styrene can lead to an increase in serum carbon dioxide concentration and easy to cause metabolic alkalosis, so it should be taken as far as possible at intervals between the two drugs, or consider giving polysulfonyl styrene through the rectum.
10. Magnesium-containing antacids can lead to a significant increase in urine pH and promote the reabsorption of quinidine in sufficient amounts, which may cause toxic reactions (ventricular arrhythmias, hypotension, exacerbation of heart failure), so it should not be combined.
11. Antacids containing aluminum, calcium or magnesium can significantly increase the pH of urine, resulting in increased renal clearance and decreased efficacy of salicylates (such as aspirin). The therapeutic effect of salicylates should be monitored when combined, and the toxicity of salicylates should be detected after the antacids are discontinued, and the dosage of salicylates should be adjusted as appropriate
12. Deserosinoin chewable tablets or dispersible tablets and pediatric oral solutions contain buffers that raise the pH of the gastrointestinal tract, so when combined with antacids containing aluminum or magnesium, the adverse reactions caused by antacid action will increase and should be avoided.
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