Background and overview of the preparation method of anhydrous lithium tetraborate
Lithium tetraborate white crystal. Melting point 930℃. Slightly soluble in water, insoluble in ethanol and other organic solvents. Usually pentahydrate. As an important inorganic material, anhydrous lithium tetraborate is mainly used as a cosolvent in X-ray fluorescence analysis and is widely used in cement plants and steel plants for analysis; in the glaze and grease components of the enamel industry; it is widely used Metal smelting, enamel manufacturing, etc. At present, anhydrous lithium tetraborate is usually produced by a process of reaction, neutralization and drying of boric acid and lithium hydroxide solution. This method has a long production cycle and high energy consumption. The patent describes a method for preparing high-purity and high-density lithium tetraborate. In this process, lithium hydroxide is first dissolved in boiling water and filtered to remove impurities to obtain recrystallized lithium hydroxide; then the recrystallized lithium hydroxide is treated with 2 Dissolve in boiling water, then add boric acid with a stoichiometric ratio of 105% to 120% to obtain a neutralized liquid; then evaporate and concentrate the neutralized liquid in a stainless steel barrel to obtain a lithium tetraborate solution, and then transfer the lithium tetraborate solution to a stainless steel baking plate , dry at 100-150℃ and 200-240℃ for the first time, then crush the dried lithium tetraborate material to 10-60 mesh, and then crush the crushed lithium tetraborate in – Dry at 450℃ for 4-5h. Finally, melt the twice-dried lithium tetraborate powder in an electric furnace at 930-950℃ for 4-5h. Finally, pour the melted material into circulating pure water. Crystals are obtained, and then high-density lithium tetraborate crystals are obtained by centrifugation. There is no report on the preparation of anhydrous lithium tetraborate using solid-phase reaction in the prior art.
Preparation method of anhydrous lithium tetraborate
A method for preparing anhydrous lithium tetraborate by solid phase method:
(1) Add 7407g of 99.9% lithium carbonate into the 1000L stainless steel double cone mixer;
(2) Add 25000g of analytically pure boric acid into the stainless steel double cone mixer;
(3) Close each valve of the double cone, open the double cone speed regulator to start mixing the raw materials, control the rotation speed to 50 rpm, and the mixing time to 120 min. After the mixing is completed, divide the mixture evenly into lepidolite. Put 3240g of the mixture in 10 stainless steel plates;
(4). Place 10 stainless steel plates in a high-temperature oven. Control the heating rate of the oven to 10°C/min. When the temperature reaches 200°C, stop heating and maintain 200°C for 4 hours, then continue at 10°C/min. After heating up to 500℃ for 3 hours, turn off the oven and cool it to room temperature.
(5). Pulverize the product after cooling to room temperature with a stainless steel pulverizer to obtain 16776g of product, with a product yield of 99.19%. The product testing results are as shown in the table:
It can be seen from the test results that the lithium tetraborate content obtained in this example reached 99.9%.
Preparation method and application of anhydrous lithium tetraborate
Application examples of anhydrous lithium tetraborate are as follows:
1) The vitrification reagent for preparing glass melts for X-fluorescence analysis consists of anhydrous lithium tetraborate or a mixture of anhydrous lithium tetraborate and lithium metaborate and boric acid. The method of use is as follows: during X-fluorescence analysis, add anhydrous lithium tetraborate or a mixture of anhydrous lithium tetraborate and lithium metaborate to the metallurgical flux, and then add analytically pure boric acid; or you can add it in advance according to a certain ratio. Let boric acid be thoroughly mixed with anhydrous lithium tetraborate or a mixture of anhydrous lithium tetraborate and lithium metaborate to prepare a fast-melting vitrification reagent and then mix it with a metallurgical flux. The analysis results of the present invention are accurate and stable and greatly shorten the analysis cycle of metallurgical flux. The analysis cycle is shortened from more than one hour to about fifteen minutes at the fastest, making rapid X-fluorescence analysis of metallurgical flux a reality; the present invention can greatly reduce the cost of melting sheets. According to the current market price, the cost saving is at least 40%.
2) X-ray fluorescence measurement method for simultaneous testing of silicon, manganese, phosphorus, chromium, nickel, copper, titanium, lead, and iron in manganese-silicon or manganese-ferroalloys. Weigh the sample, BaO, and LiCO, place them in a beaker, stir them evenly with a glass rod, then quantitatively transfer them to a pre-weighed anhydrous lithium tetraborate prefabricated crucible (the mass is recorded as m), and place the crucible in a platinum gold crucible. (The bottom of the crucible is pre-plated (6?m)g anhydrous lithium tetraborate), placed in a muffle furnace at 500°C, heated for 20 minutes, then heated to 75pyridone0°C within 15 minutes, kept warm for 15 minutes and then taken out ,cool down. Add 10 to 15 drops of potassium iodide release agent, place it in an automatic melting machine that has been preheated to 1050°C, and melt it statically at 1050°C for 10 minutes, then melt it in a swing state for 12 minutes, pour it into the platinum mold, and after the cold zone Remove the melt. The melted plate is placed on the pre-built working curve of the X-ray fluorescence instrument to measure the content of each component and the 9 components of the manganese ferroalloy are simultaneously tested. The test results are accurate and the operation is convenient and quick.
3) Used for composite demoulding of fused sheets in X-ray fluorescence analysis of iron oxide ore, including the following steps: ① Mix anhydrous lithium tetraborate, lithium metaborate mixed flux, cobalt powder, sample and lithium nitrate After adding the homogeneous mixture to the yellow platinum crucible, add lithium bromide solution; ② After passing through the first heating stage and the second heating stage, it enters the melting stage, and potassium iodide is added within 180 seconds to 200 seconds of the melting stage; ③ After the self-cooling stage and air After the cold stage, number the samples and invert the crucible to remove the samples. Under the action of the double release agent, the present invention greatly improves the demoulding effect, reduces the requirements for the smoothness of the yellow platinum crucible, and increases the average service life of the yellow platinum crucible from the original 170 melts to 600 melts. times or more, extensionThe service life of the yellow platinum crucible is more than three times that of the original service life, which reduces the cost of recasting and maintenance of the yellow platinum crucible, reduces operating costs, and improves economic benefits.
