Preparation method of lithium metaborate_Industrial additives

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.

Preparation method of lithium metaborate Preparation method

The traditional synthesis method of lithium metaborate is to use lithium carbonate and boric acid to react to prepare lithium metaborate. The reaction is:

Li2C03+2H3B03 = 2LiB02+3H20+C02

The process is to grind and mix lithium carbonate and boric acid in a molecular ratio of 1:2, and heat them in a high-temperature furnace until water vapor and carbon dioxide are no longer produced. Then heat it to 900-1000°C until it becomes a clear and transparent melt, pour it into a special vessel (made of nickel or molybdenum gold) and cool it. The cooled product is crushed, dissolved in water, filtered to remove impurities, the solution is concentrated to saturation, cooled and crystallized under stirring, and the separated crystals are dried in the air. The mother liquor is concentrated and crystallized again to obtain the second batch of products.

This process is complex and cumbersome, and the process conditions require a high temperature of 1000°C, and strict requirements on equipment materials. The final product is lithium metaborate octahydrate, which needs further processing for fluxing.

In view of the shortcomings of the existing process flow, such as the complex and cumbersome process, strict requirements on process and equipment materials, and the final product still needs deep processing, the purpose of the present invention is to provide a simple, convenient, easy-to-operate, and more suitable for industrial production of water-free bias. Lithium borate preparation process. The process of the present invention adopts the reaction of lithium hydroxide and boric acid to prepare lithium metaborate. The chemical reaction principle is:

Li0H+H3B03 = LiBO2 · 2H20 (I)

LiBO2 · 2H20~heat and separate >LiBO2 + IH2O (2)

First dissolve lithium hydroxide in hot water and filter to remove impurities. Purify slightly less than the calculated amount of boric acid and slowly add it to the hot lithium hydroxide solution. The solution will settle to cool and crystallize to obtain lithium metaborate wet material, which will then be dried, crushed and other steps to obtain the finished product of anhydrous lithium metaborate. .

A method for preparing anhydrous lithium metaborate of the present invention, the specific steps are as follows:

I. Purification of raw materials: Dissolve lithium hydroxide monohydrate in boiling pure water at a solid-liquid mass ratio of 1:4 and 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°C. Stir under heat for 15 minutes to make the reaction complete. After settling for 20 minutes, prepare for centrifugation. Wherein the amount of boric acid material in the boric acid net solution is 90% to 97% of the amount of lithium hydroxide material in the lithium hydroxide net solution;

3. Centrifugal separation: separation temperature is 50°C, centrifuge speed is 1500~2000r/min, separation time is 15 minutes, and the mother liquor is collected and stored in a centralized manner;

4. One-time drying: Add the centrifuged lithium metaborate wet material into a stainless steel baking pan and bake at 120-160°C for 6-8 hours, and then bake at 200-250°C for 2-4 hours;


5. The once-dried material is crushed and then dried twice for 5-6 hours at 450-480°C;

6. Pack the anhydrous lithium metaborate powder obtained after secondary drying under dehumidification conditions, with packaging humidity = 50%.

The boric acid described in the present invention is boric acid imported from Russia BOR MCC (boric acid/% > 99.9; water-insoluble matter content/% (0. 010; sulfate/% (0. 10; chloride/% ( 0. 050) ; Iron/% ( 0. 0020 ; Ammonia / % ^ 0. 30 ; Heavy metals / % ( 0. 0010), lithium hydroxide monohydrate is the company’s own recrystallized lithium hydroxide monohydrate (sodium % ( 0. 002 ; Calcium% ≥ 0. 002; Potassium % ≥ 0. 002; Magnesium ≥ 0. 0005; Sulfate % ≥ 0. 002; Chlorine % ≥ 0. 002; Iron % ≥ 0. 0005; Silicon % (0. 002) .

Compared with the existing technology, the advantages and beneficial effects of this fluorophenylboronic acid invention are:

1. Preparation of lithium metaborate from lithium hydroxide and boric acid through liquid phase reaction improves the utilization rate of lithium hydroxide and boric acid, avoids the release of by-products, improves product purity, and reduces purification steps. Thus, the system yield of the product is improved, and the system yield can reach more than 90%;

2. The reaction is carried out under conventional conditions, which reduces energy consumption, making industrial production more convenient, safe and low-cost;

3. The final product of this process is anhydrous lithium metaborate, which can be directly used as a flux for melting sample preparation without further processing, making it more market competitive;

4. The purity of the anhydrous lithium metaborate product produced by this process can reach 99. 99%, which is higher than the products of the existing process and is more suitable for today’s market demand.

TAG: lithium metaborate, flux, preparation method

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