Preparation of silica from leaching residue-Iota

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Service > Preparation of silica from leaching residue

Preparation of silica from leaching residue

White carbon black, also known as hydrated silica, is a white reinforcing filler, and its wide range of uses, rubber, plastics, paper, paint, printing ink, paint manufacturing, such as industry indispensable raw materials. Foreign production is not only large, but also to all kinds of inorganic fine chemical products development. Domestic manufacturers of 10, production of white carbon black are mostly used for rubber reinforcing agent. In recent years, with the improvement of people's living standards, industrial rubber products structure occurred change, decreasing the amount of black rubber, replaced by light color, color, transparent or translucent rubber product demand is increasing and white carbon black by market demand increased quickly.
Gulu Geyserite acid extraction of cesium, leaching residue, due to the leaching of iron and manganese, improve the whiteness; due to the leaching of alkaline elements, SiO2 content also than silicon China improved, making it closer to the preparation of water glass, silica, silica activity of SiO2 materials of high silicon low iron requirements. In order to use silicon silicon resources in Central China, we conducted a test system of silica silicon slag.
The preparation of white carbon black (common name must use sodium silicate water glass), therefore, first by the silicon slag preparation of sodium silicate solution. In this experiment, the wet process of producing sodium silicate solution with sodium hydroxide solution is used in the experiment. Preparation of white carbon black process route is: using hydrochloric acid water glass of sol and then with water glass reaction preparation of white carbon black, after washing, drying, crushing and white carbon black products.
One, made of silicon slag glass
The test was carried out in 21 high pressure vessel, and the silicon slag and NaOH solution were prepared with water glass at a certain temperature and pressure. By acid leaching of silica residue containing SiO2 85%, NaOH using pure chemical reagents, silicon slag 300g each test, according to the modulus m=SiO2/Na2O=3.3 with addition of NaOH, for the test conditions of temperature, pressure, time, SiO2 excess percentage.
Under the experimental conditions, the leaching rate of silicon slag SiO2 is 50% ~ 60%, that is to say, the activity of SiO2 is about 60%, the other SiO2 is inert, which is not easy to be dissolved. According to the experimental results, the conditions for the wet water glass of silicon slag are: the time 2h, the temperature is 160, the NaOH concentration is 18%, the silicon excess rate is 20%. Do the sample test under this condition, the modulus of water glass is about 2.5.
Two, silica reagent
The chemical analysis: Na2O content 8.86%, SiO2 21.2%, modulus 2.47, concentration 35, Be, 1.32. The test of water glass as raw materials to prepare white carbon black.
1 sol preparation
First homemade water glass (concentration of 35 'beryllium, m=2.47) diluted to 15' beryllium, then to 12 'beryllium hydrochloric acid solution and in mechanical stirring adding dilution water glass, control investment and the feeding speed, until the solution of pH = 3 ~ 3.5 to sol.
In the preparation process of silica sol, the preparation is an important step. The quality of product transparency and the quality of the rubber and rubber are largely determined by the quality of the sol. The concentration of sol, pH value, gel temperature, and the time of the time have a great influence on the stability of the sol. After the experiment, the SiO2 content of the sol was 6.5% ~ 8.5%, the pH was 3 ~ 3.5, the stability of the prepared sol was good, and it was not easy to condense into blocks, and was clear and transparent.
2 reaction process
Reaction process is the white carbon black preparation process, the key step, reaction pH control in a large extent determines the quality of products. We are in the range of pH 6 ~ 9 of a lot of experiments compared to determine and choose the reaction pH 7.8 ~ 8.2, reaction temperature is 70 DEG C, prepared under the condition of white carbon black, its fineness, depending on the specific volume, oil absorption value and other indicators were good. Also reaction feeding speed should not be too fast, fast feeding speed, easy to produce local gel, which led to silica apparent specific volume, oil absorption value indicators decline, so should slow feeding.
3 washing
Will response to sediment and filtering solution after separation, first washed with water, and then a small amount of washing water, NaCl content is less than 1.5%, because sodium chloride residues over the performance of the conference on product purity and vulcanized rubber.
4 drying
Silica absorbent strong, is not easy to dry, after washing the precipitate in 150 DEG C under static drying 6h, white carbon black and water down to below 6%.
Three, white carbon black product quality
The trial production of white carbon black product quality can reach the general level of white carbon black ministerial standards, most of the project quality to achieve active white carbon black quality standards, SiO2 content, refractive rate is slightly lower than the active white carbon black quality requirements, which may associated with a lower silicon content of silicon slag, the introduction of water glass impurities, still need further study, can achieve active white carbon black standard.
The advantages of SiO2 and SiO2 in the silicon slag are high activity and easy to be extracted. The disadvantage is that the content of SiO2 is low and the impurity content is high. As for whether the future development Geyserite silicon resources utilization, used in the preparation of water glass and silica should be as the local silicon resources and Tibet regions depending on the needs of silicon products. If there is a market, and the lack of quartz sand, silicon development central silicon water glass and silica is undoubtedly reasonable; if quality quartz sand resources rich, to seek a better use of Geyserite silicon.

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