5 Must-Have Features in a Lithium magnesium silicate

Preparation method of lithium magnesium silicate Technical Field The invention relates to the field of chemical synthesis, in particular to a preparation method of lithium magnesium silicate. Background Lithium magnesium silicate, CAS No.-90-9, molecular formula Li2Mg2O9Si3Belongs to bentonite montmorillonite, has a hexagonal crystal structure, is white powder in appearance, is nontoxic and tasteless, and is commonly used as a thickening agent, a suspending agent, an anti-settling agent, an adhesive, a thixotropic agent and a dispersing agent. The hydrated gel has excellent rheological property and is widely used in medicines, cosmetics, paints, pesticides, toys and the like. The synthesis method of the magnesium lithium silicate is mainly a hydrothermal synthesis method, and the magnesium lithium silicate is prepared by mixing soluble silicate and magnesium lithium oxide in proportion and reacting for a long time under the conditions of high temperature and high pressure, but the long-time conditions of high temperature and high pressure are easy to cause potential safety hazards, and the produced magnesium lithium silicate also has the problems of uneven chelation degree, too hard texture and unstable batch quality, so that a preparation method of the magnesium lithium silicate which has normal-pressure reaction and high safety and can be suitable for large-scale and large-scale production needs to be found. Chinese patent CNA discloses a magnesium lithium silicate compound and a preparation method thereof, which adopts a normal pressure reaction to avoid the potential safety hazard problem of long-time high temperature and high pressure conditions, but on one hand, because the preparation method does not adopt a high pressure condition, the conditions of normal pressure condition and other parameter control are not optimized, and on the other hand, on the selection of raw materials and their mixture ratio, the produced magnesium lithium silicate still has the problems of non-uniform chelating degree and unstable quality between batches. Therefore, there is a need for a magnesium lithium silicate which can be produced under normal pressure conditions, is highly safe, and can produce a lithium magnesium silicate having a uniform and stable crystal structure unit. Disclosure of Invention In view of the above problems, the present invention aims to provide a method for preparing lithium magnesium silicate, which can be conveniently produced under normal pressure conditions and can prepare lithium magnesium silicate with uniform and stable crystal structure units. In order to achieve the purpose, the invention provides the following technical scheme: a preparation method of lithium magnesium silicate comprises the following steps: (1) dissolving lithium chloride in water in a reaction kettle, heating to boil, and keeping boiling for 2-4 min; adding a magnesium sulfate solution, and keeping boiling for 18-22 min; (2) dropwise adding liquid water glass into the reaction kettle at a constant speed; the uniform dripping speed is as follows: 0.4 kg/min-0.6 kg/min; (3) dropwise adding a sodium carbonate solution into the reaction kettle at a constant speed; (4) after the dropwise adding is finished, keeping boiling, and reacting for 17-20 hours to obtain the product; wherein the molar ratio of silicon, lithium and magnesium is (2-4): 0.9-1.1): 1; the molar ratio of the sodium carbonate to the lithium chloride is (0.4-0.6): 1. The invention also provides a magnesium lithium silicate, and the specific technical scheme is as follows: the magnesium lithium silicate is prepared by the preparation method. Based on the technical scheme, the invention has the following beneficial effects: the inventor of the invention finds that the specific types of the raw materials, the adding modes and the adding sequences thereof and the performance of the synthesized magnesium lithium silicate are different, and the adoption of the proper raw materials, the proper proportion, the adding modes and the adding sequences thereof and the matching of pressure conditions is of great importance for the stable crystal structure formed by the magnesium lithium silicate. The invention adopts a hydrothermal synthesis method under normal pressure, water glass and sodium carbonate are dripped in a uniform speed dripping mode under the condition that liquid in a reaction kettle keeps boiling through a proper raw material adding sequence, and the dripping speed of the dripped water glass is controlled, so that silicon, magnesium and lithium oxygen bonds in magnesium lithium silicate can be formed at a proper and uniform speed, the magnesium lithium silicate forms a stable crystal structure, the stable crystal structure and a firm multi-molecular spatial structure are provided, and the effects of stable thickening, thixotropic property, suspension, anti-settling and other aqueous rheological additives are realized. The powder particles of the lithium magnesium silicate prepared by the preparation method are more uniform and fine, and are favorable for being compatible with other components in a formula. The gel dispersion liquid prepared by the invention has the advantages of high degree of separation of particles into single small pieces in a colloidal structure, firm structure, high viscosity, obvious thickening effect, high transparency of thixotropic gel formed by expansion, and high application value in the fields of multicolor coatings and the like. Moreover, the invention adopts mild raw materials, does not add any strong acid and strong alkali in the production process, reduces pollution emission and is beneficial to environmental protection. Detailed Description In order that the invention may be more readily understood, reference will now be made to the following more particular description of the invention, examples of which are set forth below. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete. Each of the raw materials used in the examples is a commercially available product unless otherwise specified. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. The embodiment of the invention provides a preparation method of lithium magnesium silicate, which comprises the following steps: (1) dissolving lithium chloride in water in a reaction kettle, heating to boil, and keeping boiling for 2-4 min; adding a magnesium sulfate solution, and keeping boiling for 18-22 min; preferably, in the lithium chloride and the magnesium sulfate, the molar ratio of lithium to magnesium is (0.9-1.1): 1; (2) dropwise adding liquid water glass into the reaction kettle at a constant speed; preferably, the uniform dropping speed is as follows: 0.4 kg/min-0.6 kg/min; (3) dropwise adding a sodium carbonate solution into the reaction kettle at a constant speed; (4) after the dropwise adding is finished, keeping boiling, and reacting for 17-20 hours to obtain the product; further preferably, the molar ratio of silicon, lithium and magnesium is (2-4): 0.9-1.1): 1; the molar ratio of the sodium carbonate to the lithium chloride is (0.4-0.6): 1. Wherein the crystal structure unit of magnesium lithium silicate is a tiny flake with the thickness of nanometer, and the surface of the flake is covered with exchangeable cations, wherein the exchangeable cations are mainly Na+. When the lithium magnesium silicate particles are mixed with water, the water is mixed with Na+Contact is made to the surface of the sheet to hold the gel open along the sheet, at which point the particles expand rapidly until the sheet separates. Because the surface of the slice is negatively charged and the end surface is positively charged, the separated slice end surface is attracted to the surface of another slice, thereby rapidly forming a colloid structure of three-dimensional space, namely a card palace structure, increasing the viscosity of the system, and having high suspension and thickening propertiesThixotropy, good compatibility and chemical stability, and forms an ideal water system thickening rheological agent. Therefore, the uniformity and stability of the crystal structure unit of the magnesium lithium silicate play an important role in the performance of forming colloid and colloid after the magnesium lithium silicate is dissolved in water. According to the invention, by adopting the proper raw materials and the proportion, through a proper raw material adding sequence, under the condition that liquid in a reaction kettle keeps boiling, water glass and sodium carbonate are dropwise added at a constant speed, and the dropwise adding speed of the water glass is controlled, so that silicon, magnesium and lithium oxygen bonds in magnesium lithium silicate can be formed at a proper and uniform speed under normal pressure reaction conditions, the magnesium lithium silicate forms a stable crystal structure, and the effect is finally realized. Water glass is a soluble alkali silicate material, also known as soda-lime, formed by combining alkali oxides and silica. The water glass can be divided into sodium water glass and potassium water glass according to the types of alkali metals, and the molecular formulas of the water glass and the potassium water glass are respectively Na2O·nSiO2And K2O·nSiO2The coefficient n in the formula is called a water glass modulus, and is a molecular ratio (or a molar ratio) of silica and an alkali metal oxide in water glass, and the water glass modulus has a correlation with a silica content and a water glass viscosity. In the invention, the modulus of the liquid water glass is preferably 3-4. The water glass modulus in the range is favorable for the prepared magnesium lithium silicate to have good viscosity. More preferably, the water glass is water-soluble sodium silicate, namely sodium water glass with the molecular formula of Na2O·nSiO2。 Preferably, the sodium carbonate solution is dropwise added into the reaction kettle at a constant speed in the step (2), wherein the dropwise adding speed is controlled to be 0.1kg to 0.2kg of sodium carbonate per minute. The sodium carbonate is dripped at a reasonable speed to be beneficial to the formation of a uniform and stable crystal structure of the magnesium lithium silicate, the texture of the crystal structure is soft, and the obtained powder particles are fine and uniform, so that the transparency of the gelled powder in application is facilitated, and the compatibility with other components in a formula is also facilitated. More preferably, the reaction in the reaction kettle of the invention is kept boiling and continuously stirred in the whole process, and further, favorable conditions are provided for the magnesium lithium silicate to form a uniform and stable crystal structure. Optionally, after the reaction in the reaction kettle is completed, the method further comprises the following steps: cooling the reaction kettle, adding water, stirring uniformly, and filtering until the water is drained; and drying the filter cake to obtain blocky lithium magnesium silicate solid, and crushing. Wherein, specifically, the filtration is as follows: filtering water through a plate and frame filter. When the filter cake is dried, an oven with the temperature of 180-220 ℃ is preferably adopted, and the drying temperature is more preferably 200 ℃. After the massive magnesium lithium silicate solid is obtained, in some modes, the magnesium lithium silicate is crushed by a crusher, preferably into 300-350 meshes of powder, and more preferably 325 meshes of powder. Example 1 The embodiment provides a preparation method of lithium magnesium silicate, which mainly comprises the following raw materials: food grade magnesium sulfate heptahydrate (MgSO)4·7H2O), water glass (liquid, water-soluble sodium silicate, modulus ratio 3), lithium chloride (LiCl), edible sodium carbonate (Na)2CO3)； The preparation steps are as follows: a.29.6kg of magnesium sulfate heptahydrate was completely dissolved in 130kg of deionized water for use. b. In a L reaction kettle containing a condensation reflux system and a heating system, 5.18kg of lithium chloride is added, 50kg of water is added, heating and stirring are carried out, boiling is kept for 3 minutes, then magnesium sulfate solution is added, boiling is kept for 20 minutes, and the reaction kettle is kept boiling and stirring is continuously carried out in the whole production process. c. Adding 36.65kg of water glass into a dropping pot, uniformly dropping the water glass into the reaction kettle, and controlling the dropping speed so that the dropping time of the water glass is 80 minutes. d. Dissolving 7.24kg of edible sodium carbonate in 140kg of deionized water, stirring to completely dissolve, adding into a dropping tank, and controlling the dropping speed for 60 minutes. e. After the dropwise addition, the reaction kettle was kept boiling for 18 hours. f. And after the reaction is finished, cooling, adding 200kg of deionized water, uniformly stirring, filtering to remove water through a plate and frame filter, and drying a filter cake in an oven at the temperature of 200 ℃ for 4 hours to obtain a blocky magnesium lithium silicate solid. g. The lithium magnesium silicate blocks are crushed into 325-mesh powder by a crusher. The heating and boiling maintaining of the reaction kettle are realized through heat conducting oil and an intelligent temperature control system, wherein the oil temperature of the heat conducting oil is 110 ℃. Example 2 The present embodiment provides a method for preparing lithium magnesium silicate. The procedure was substantially the same as the starting material and the preparation method in example 1, except that the raw material used was water glass having a modulus ratio of 4. The other raw materials, the preparation steps and the conditions are the same. Example 3 The present embodiment provides a method for preparing lithium magnesium silicate. The process was substantially the same as the starting material and process described in example 1, except that the rate of addition of water glass in step c was different, the completion time of the addition of water glass was 100 minutes, the rate of addition of edible sodium carbonate in step d was different, and the completion time of the addition of edible sodium carbonate was 40 minutes. Comparative example 1 The comparative example provides a preparation method of lithium magnesium silicate, which adopts the following raw materials: magnesium hydroxide (Mg (OH)2) Water glass (liquid sodium silicate, modulus ratio 3), lithium carbonate (Li)2CO3) And edible sodium carbonate (Na)2CO3) (ii) a The raw materials of magnesium element and lithium element are different from those of example 1. The preparation method is basically the same as that of the embodiment 1, wherein: the amount of magnesium hydroxide was 7kg, and the amount of lithium carbonate was 4.15kg, which was the same as the amount of magnesium and lithium in example 1. Comparative example 2 This comparative example provides a method for preparing lithium magnesium silicate using the same raw materials and amounts as in example 1. The preparation method comprises the following steps: a.29.6kg magnesium sulfate heptahydrate and 5.18kg lithium chloride were dissolved in water, and then mixed with 36.65kg water glass, and the mixture was heated to boiling in a reaction vessel with continuous stirring. The reaction time was 100 minutes. b. Dissolving 7.24kg of edible sodium carbonate in 140kg of deionized water, stirring to completely dissolve, adding into a dropping tank, and controlling the dropping speed for 60 minutes. c. After the dropwise addition, the reaction kettle was kept boiling for 18 hours. e. And after the reaction is finished, cooling, adding 200kg of deionized water, uniformly stirring, filtering to remove water through a plate and frame filter, and drying a filter cake in an oven at the temperature of 200 ℃ for 4 hours to obtain a blocky magnesium lithium silicate solid. f. The lithium magnesium silicate blocks are crushed into 325-mesh powder by a crusher. The heating and boiling maintaining of the reaction kettle are realized through heat conducting oil and an intelligent temperature control system, wherein the oil temperature of the heat conducting oil is 110 ℃. Comparative example 3 This comparative example provides a method for preparing lithium magnesium silicate using the same raw materials and amounts as in example 1. The preparation method comprises the following steps: a.29.6kg of magnesium sulfate heptahydrate was completely dissolved in 130kg of deionized water for use. b. In a L reaction kettle containing a condensation reflux system and a heating system, 5.18kg of lithium chloride is added, 50kg of water is added, heating and stirring are carried out, boiling is kept for 3 minutes, then magnesium sulfate solution is added, boiling is kept for 20 minutes, and the reaction kettle is kept boiling and stirring is continuously carried out in the whole production process. c. Adding 36.65kg of water glass into a dropping pot, uniformly dropping the water glass into the reaction kettle, and controlling the dropping speed so that the dropping time of the water glass is 120 minutes. d. Dissolving 7.24kg of edible sodium carbonate in 140kg of deionized water, stirring to dissolve completely, directly adding all the materials into a reaction kettle, stirring uniformly, and reacting for 60 minutes. e. After the dropwise addition, the reaction kettle was kept boiling for 18 hours. f. And after the reaction is finished, cooling, adding 200kg of deionized water, uniformly stirring, filtering to remove water through a plate and frame filter, and drying a filter cake in an oven at the temperature of 200 ℃ for 4 hours to obtain a blocky magnesium lithium silicate solid. g. The lithium magnesium silicate blocks are crushed into 325-mesh powder by a crusher. The heating and boiling maintaining of the reaction kettle are realized through heat conducting oil and an intelligent temperature control system, wherein the oil temperature of the heat conducting oil is 110 ℃. EXAMPLES 1-2, COMPARATIVE EXAMPLES 1-3 characterization and Performance testing of lithium magnesium silicate 1. Infrared detection The prepared magnesium lithium silicate is detected by a Fourier transform infrared spectrometer (FTIR). The model is as follows: nexus, manufactured by Thermo Nicolet, USA, with a maximum resolution of 0.019cm-1The scan rate was 1 time/second. The test wavelength range is -40 cm of mid-infrared-1。 The results of the infrared test showed that the samples prepared in examples 1 and 2 of the present invention were cm-1A strong and wide absorption peak exists nearby, and the absorption peak is cm-1And in the form of-1There is also a distinct absorption peak. Wherein, cm-1Is the peak of hydroxyl hydrogen bond between hydroxyl stretching vibration and crystal layers, and is cm-1And in the form of-1The absorption peak is the shock absorption peak of absorbed water molecule-OH and the stretching vibration absorption peak of Si-O bond in the crystal lattice of magnesium silicate lithium. The above absorption peaks are all characteristic absorption peaks of magnesium lithium silicate, which indicates that the magnesium lithium silicate is really prepared by the invention. 2. Rheology test The lithium magnesium silicate powder prepared in examples 1 to 2 and comparative examples 1 to 3 was added to deionized water to prepare an aqueous dispersion of 3% by mass of lithium magnesium silicate, and the time required for gelling and the transparency thereof were recorded. And standing for 24 hours, detecting according to a conventional method, and testing the light transmittance and the viscosity of the product.

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Chemistry in its element: lithium

(Promo)You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry.(End promo)Chris SmithHello, this week to the element that tops group one and gives us lighter aircraft and armoured plating. It also keeps grease running at arctic temperatures, powers pacemakers and lies at the heart of the hydrogen bomb.Matt Wilkinson Lithium is rare in the Universe, although it was one of the three elements, along with hydrogen and helium, to be created in the Big Bang. The element was discovered on Earth in by Johan August Arfvedson (-) in Stockholm when he investigated petalite, one of the first lithium minerals to be discovered. (It was observed to give an intense crimson flame when sprinkled on to a fire.) He deduced that petalite contained an unknown metal, which he called lithium from the Greek word for a stone, lithos, although he never actually produced any. He reasoned that it was a new alkali metal and lighter than sodium. However, unlike sodium, which Humphry Davy had isolated in by the electrolysis of sodium hydroxide, Arfvedson was unable to produced lithium by the same method. A sample of lithium metal was finally extracted in and then by the electrolysis of molten lithium chloride.Once lithium's discovery had been announced others soon found it to be present in all kinds of things such as grapes, seaweed, tobacco, vegetables, milk and blood. Another lithium ore is spodumene, which like petalite is a lithium aluminium silicate, and there is a large deposit of this ore in South Dakota. World production of lithium compounds is around 40 000 tonnes a year and reserves are estimated to be around 7 million tonnes. Industrial production of the metal itself is reported to be about tonnes a year, and this is produced by the electrolysis of molten lithium chloride and potassium chloride in steel cells at temperatures of 450oC. Lithium is moderately toxic as discovered in the s when patients were given lithium chloride as a salt substitute. However, in small doses it is prescribed as a treatment for manic depression (now called bipolar disorder). Its calming effect on the brain was first noted in , by an Australian doctor, John Cade, of the Victoria Department of Mental Hygiene. He had injected guinea pigs with a 0.5% solution of lithium carbonate, and to his surprise these normally highly-strung animals became docile, and indeed were so calm that they would sit in the same position for several hours. Cade then gave his most mentally disturbed patient an injection of the same solution. The man responded so well that within days he was transferred to a normal hospital ward and was soon back at work. Other patients responded similarly and lithium therapy is now used all around the world to treat this mental condition. How it works is still not known for certain, but it appears to prevent overproduction of a chemical messenger in the brain.Lithium is used commercially in various ways. Lithium oxide goes into glass and glass ceramics. Lithium metal goes into alloys with magnesium and aluminium, and it improves their strength while making them lighter. Magnesium-lithium alloy is used in protective armour plating and aluminium-lithium reduces the weight of aircraft thereby saving fuel. Lithium stearate, made by reacting stearic acid with lithium hydroxide, is an all-purpose high-temperature grease and most greases contain it. It will even work well at temperatures as low as -60oC and has been used for vehicles in the Antarctic.Lithium batteries, which operate at 3-volts or more, are used in devices where compactness and lightness are all-important. They are implanted to supply the electrical energy for heart pacemakers. They function with lithium as the anode, iodine as the solid electrolyte, and manganese oxide as the cathode - and they have a lifespan of ten years. This longevity has been extended to lithium batteries of the more common 1.5-volts variety (in which the cathode is iron disulfide) that are in everyday gadgets such as clocks, and lithium is now beginning to be used for rechargeable batteries Lithium is a soft, silvery-white, metal that heads group 1, the alkali metals group, of the periodic table of the elements. It reacts vigorously with water. Storing it is a problem. It cannot be kept under oil, as sodium can, because it is less dense and floats. So it is stored by being coated with petroleum jelly. Somewhat surprisingly it does not react with oxygen unless heated to 100oC, but it will react with nitrogen from the atmosphere to form a red-brown compound lithium nitride, Li3N.The hydrogen of hydrogen bombs is actually the compound lithium hydride, in which the lithium is the lithium-6 isotope and the hydrogen is the hydrogen-2 isotope (deuterium). This compound is capable of releasing massive amounts of energy from the neutrons released by the atomic bomb at its core. These are absorbed by the nuclei of lithium-6 which immediately disintegrates to form helium and hydrogen-3 which then go on to form other elements and as they do the bomb explodes with the force of millions of tonnes of TNT. Chris SmithMatt Wilkinson on the extraordinary virtues of element number 3, Lithium. Next time to one of the universe's rarer chemicals and horribly toxic though it is, without it we'd be the proverbial particle short of a nucleus.Richard Van NoordenJames Chadwick in discovered the neutron by bombarding a Beryllium sample with the alpha rays eminating from radium . He observed that the beryllium emitted a new kind of sub-atomic particle which had mass but no charge, the neutron and the combination of radium and beryllium is still used to make neutrons for research purposes, although a million alpha-particles only manage to produce 30 neutrons. Chris SmithSo that goes to show that sometimes a lot can only go a little way. Richard Van Noorden will be here with the story of Beryllium on next week's Chemistry in its Element, I hope you can join us. I'm Chris Smith, thank you for listening and goodbye.(Promo)Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements.
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