Application background and overview of lithium metaborate
Lithium metaborate is a colorless triclinic crystal with pearlescent luster. It is soluble in water. It begins to decompose above 1200℃. Lithium oxide is produced. Its octahydrate is a colorless trigonal crystal with a melting point of 47°C. It can be produced by melting stoichiometric amounts of lithium hydroxide or lithium carbonate and boric acid.
Applications of lithium metaborate
Lithium metaborate is a flux for melt sample preparation, suitable for wavelength dispersive XRF fluorescence spectrometer, AA atomic absorption and ICP sample preparation. Its main function is to mix it with lithium tetraborate in proportion to neutralize the acidity and alkalinity of different oxides so that the sample can be melted, so that the corresponding molten glass piece or solution can be obtained. Examples of its application are as follows:
Applications of lithium metaborate 1. Use lithium metaborate to prepare analytical solutions for ICP-AES and AAS.
The technical solution adopted is: first use lithium metaborate to melt and decompose the oxidizing sample to be tested in a platinum or platinum yellow crucible; then pour the molten liquid directly into the dilute acid; and finally heat it The melt of the oxidizing sample is completely dissolved in the dilute acid to obtain the analysis solution. Taking advantage of the strong melting decomposition properties of lithium metaborate on oxides and the good demoulding effect of lithium metaborate in platinum or platinum yellow crucibles, the method of pouring the molten liquid directly into the dilute acid solution to quickly generate an analytical solution is effective; It solves the problem of sample dissolution of acid-resistant oxides and is universally applicable to general oxides; the resulting analytical solution is suitable for inductively coupled plasma atomic emission spectroscopy and atomic absorption spectroscopy. The difference compared with the general sodium borate alkali fusion method is that it can adopt a one-step pouring method, which simplifies the operation steps, reduces the probability of sample contamination, and realizes the determination of sodium element.
Applications of lithium metaborate 2. Preparation of lithium tetrafluoroborate.
Lithium tetrafluoroborate is mainly used in lithium battery electrolyte and pharmaceutical and chemical industries. The preparation method includes the following steps: mix lithium carbonate, lithium hydroxide monohydrate or anhydrous lithium hydroxide with boric acid and boron oxide, burn it to obtain lithium metaborate, crush it to obtain lithium metaborate powder, and mix the metaborate Lithium powder is mixed with ammonium fluoride or ammonium bifluoride, and the lithium tetrafluoroborate product can be obtained by vacuum pressure and negative pressure burning reaction. The present invention uses solid lithium source and solid boron source as raw materials to prepare lithium tetrafluoroborate. This process has the advantages of easy availability of raw materials, non-toxic raw materials, non-corrosiveness, high product quality, no side reactions, environmental protection and high efficiency.
Applications of lithium metaborate 3. It is used in the field of analysis and testing technology, especially the method of simultaneously determining the content of phosphorus, magnesium, iron, aluminum, silicon, calcium titanium, manganese and strontium in phosphate rock using inductively coupled plasma emission spectrometry.
Specifically, lithium metaborate is a high melting point non-oxidizing solvent that has strong decomposition ability for most samples and can effectively decompose some insoluble rocks and minerals. Put the phosphate rock sample in a platinum crucible, add lithium metaborate solvent and lithium bromide release agent, and use a high-frequency sample dissolving machine to melt and decompose the phosphate rock sample. Pour it into a polytetrafluoroethylene beaker containing 10% nitric acid at high temperature under a magnetic stirrer. After the dissolved sample was acidified and fixed to volume, the national first-class phosphate rock standard material was used for matrix matching and the yttrium internal standard method was used to establish a standard curve. ICP? The method for measuring the contents of silicon oxide, calcium oxide, titanium dioxide, manganese oxide, and strontium oxide has the advantages of convenience and accuracy, and is especially suitable for the determination of batch phosphate rock samples.
Applications of lithium metaborate 4. Preparation of copper concentrate melting tablets for X-ray fluorescence spectroscopy.
The method is to use a mixed flux of lithium tetraborate and lithium metaborate as the bottom in a platinum crucible, then weigh sodium carbonate, silicon dioxide, lithium nitrate and copper concentrate samples in sequence, and add sodium carbonate, silicon dioxide, lithium nitrate Mix it with the copper concentrate sample, cover it with a mixed flux of lithium tetraborate and calcium carbonate lithium metaborate, place it in a muffle furnace at 600℃ for 15 minutes, take it out and use it in the melting furnace 800 ℃Melting, add release agent and shake well, pour into the mold, take it out after cooling, and obtain the sample piece. The invention ensures that the sulfur in the copper concentrate can be stably retained in the test piece without being lost due to high temperature during the preparation process. This method is suitable for the determination of copper, sulfur, lead, zinc, manganese, arsenic, iron, silicon, aluminum, magnesium, calcium and other elements in copper concentrate.
Applications of lithium metaborate 5. Preparation of an inorganic all-solid electrochromic element.
The structure of the element is: a tungsten oxide film, a mixture film of lithium metaborate and lithium sulfate, a nickel oxide film, and a tin-doped indium oxide film deposited sequentially on a tin-doped indium oxide glass substrate; the steps of the preparation method are as follows : Cut the tin-doped indium oxide conductive glass into a substrate suitable for the size of the instrument and equipment, and ultrasonically clean it in acetone, boric acid-free ethanol, and deionized water in sequence; sputter the multi-target magnetron sputtering device equipped with the substrate The film-forming chamber is evacuated to 1×10-4Pa; then a tungsten oxide film, a mixed film of lithium metaborate and lithium sulfate, a nickel oxide film, and a tin-doped indium oxide film are deposited in sequence. The electrochromic element prepared according to the method of the present invention has the performance of changing the transmittance of visible light, and has the characteristics of large modulation range, short reaction time, etc., and can be used in the research and application of color-changing glass, anti-glare reflectors, information display screens, and energy-saving windows. It is of great value.
Applications of lithium metaboratePreparation
Lithium metaborate is prepared by reacting lithium hydroxide and boric acid. The chemical reaction principle is:
The specific steps are as follows:
1) Purification of raw materials: Dissolve lithium hydroxide monohydrate in boiling pure water at a solid-liquid mass ratio of 1:4, then filter it while hot until it is clear, to obtain a pure lithium hydroxide solution; dissolve boric acid at a solid-liquid mass ratio of 1 :1 Dissolve in boiling pure water and filter while hot until clear to obtain boric acid pure solution;
2) Neutralizing ingredients: Add boric acid pure solution to the lithium hydroxide pure solution to neutralize. The reaction temperature is above 70℃. Stir under heat for 15 minutes to allow the reaction to be sufficient, and then settle for 20 seconds. After a few minutes, prepare for centrifugal separation, in which the amount of boric acid material in the boric acid pure solution is 90% to 97% of the amount of lithium hydroxide material in the pure lithium hydroxide solution;
3) Centrifugal separation: separation temperature ≧50℃, centrifuge speed 1500~2000r/min, separation time ≧15 minutes, the separated mother liquor is collected and stored centrally;
4) One-time drying: Add the centrifuged wet lithium metaborate material into a stainless steel baking pan and bake at 120-160℃ for 6-8 hours, then dry at 200-250℃ Dry for 2-4 hours;
5) The once-dried materials are crushed and then dried for a second time at 450-480℃ for 5-6 hours;
6) Pack the anhydrous lithium metaborate powder obtained after secondary drying under dehumidification conditions, with the packaging humidity ≦ 50%.
