WO2013155976A1 - Method for preparing precipitated silica - Google Patents

Method for preparing precipitated silica Download PDF

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WO2013155976A1
WO2013155976A1 PCT/CN2013/074386 CN2013074386W WO2013155976A1 WO 2013155976 A1 WO2013155976 A1 WO 2013155976A1 CN 2013074386 W CN2013074386 W CN 2013074386W WO 2013155976 A1 WO2013155976 A1 WO 2013155976A1
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filtrate
mhco3
precipitated silica
nsio2
sio2
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PCT/CN2013/074386
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French (fr)
Chinese (zh)
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章浩龙
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浙江宇达化工有限公司
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Publication of WO2013155976A1 publication Critical patent/WO2013155976A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof

Definitions

  • the invention relates to a method for preparing precipitated silica, belonging to the technical field of chemical industry.
  • Precipitated silica also known as white carbon black and precipitated white carbon black
  • white carbon black and precipitated white carbon black is a hydrated amorphous silicic acid product with a chemical expression of mSiO2. .nH2O
  • the appearance is a white highly dispersed amorphous powder, and a small amount is also processed into pellets as a commodity.
  • Precipitated silica has a wide range of uses as a good reinforcing agent for synthetic rubber. Its performance is equal to or better than that of carbon black. Others are used as thickeners or thickeners, matting agents for paints, various synthetic resins and plastic products. Fillers, modifiers, fillers and paper surface ingredients in the paper industry, and more.
  • Precipitated silica is mainly obtained by the following reaction: Na 2 O .n SiO 2 +H 2 SO 4 +(nx-1)H 2 O----->n SiO 2 .xH 2 O ⁇ + Na 2 SO 4
  • Acid-salting method NaCl: 0.275 tons; 30% hydrochloric acid: 1.15 tons;
  • the problem to be solved by the present invention is to provide a method for preparing precipitated silica which can be recycled by using other chemicals besides a silicon source (soluble silicate or quartz sand) to reduce precipitated silica. Manufacturing costs, while consuming less resources, reducing emissions, and minimizing damage to the environment.
  • a silicon source soluble silicate or quartz sand
  • the present invention adopts the following technical scheme: a method for preparing precipitated silica, which is based on soluble silicate M 2 O.nSiO 2 and hydrogencarbonate MHCO 3 as M 2 O.nSiO.
  • the molar ratio of 2 to MHCO 3 is 1:2.0 ⁇ 2.3
  • the hydrated SiO 2 is precipitated, the filtrate is separated by filtration, and the filter cake is washed and dried to obtain a precipitated silica product; the filtrate mainly contains carbonic acid.
  • M in the soluble silicate M 2 O.nSiO 2 , carbonate M 2 CO 3 , hydrogencarbonate MHCO 3 is alkali metal element Na or K
  • n in the soluble silicate M 2 O.nSiO 2 is its modulus.
  • the modulus n of the soluble silicate M 2 O.nSiO 2 is such that when M is an alkali metal element Na, the value of n is from 1.0 to 3.7, and when M is an alkali metal element K, the value of n is from 2.2 to 3.7.
  • the filtration is by vacuum filtration or a filter press.
  • the drying is by spray drying, box drying or air drying.
  • the box was also pulverized after drying.
  • the filtrate may be passed with CO 2 to cause the carbonate M 2 CO 3 in the filtrate to form MHCO 3 , which is recycled as a reaction raw material for preparing precipitated SiO 2 .
  • the filtrate may be concentrated into CO 2, to produce a mixture of saturated bicarbonate solution thereto MHCO 3 crystals, the concentration is controlled so that the crystallization mixture MHCO 3 accounted for in the MHCO 40 ⁇ 45 3 %, then MHCO 3 solids were recovered by filtration, and the filtrate was recycled as a raw material for preparing precipitated SiO 2 .
  • the filtrate may also be partially concentrated to a carbonate and a bicarbonate in the filtrate to obtain a mixture of a saturated solution and a crystal, and then the mixture is reacted with quartz sand to form a soluble silicate M 2 O.nSiO 2 .
  • the produced soluble silicate M 2 O.nSiO 2 is used to generate a reaction raw material for precipitating SiO 2 , and the concentration is controlled so that the water content of the mixture conforms to the process requirement for producing M 2 O.nSiO 2 .
  • the method for preparing precipitated silica of the present invention comprises the steps of: reacting soluble silicate M 2 O.nSiO 2 and hydrogencarbonate MHCO 3 as raw materials, precipitating hydrated SiO 2 , and drying to obtain a precipitate.
  • Silica products reacting soluble silicate M 2 O.nSiO 2 and hydrogencarbonate MHCO 3 as raw materials, precipitating hydrated SiO 2 , and drying to obtain a precipitate.
  • the filtrate mainly contains carbonate and a small amount of M 2 CO 3 MHCO 3 bicarbonates
  • carbonates filtrate M 2 CO 3 and a small amount of bicarbonate MHCO 3 may be obtained by reaction of raw materials of different treatments, so in addition to In addition to silicon sources (soluble silicate or quartz sand), other chemicals can be recycled, reducing the manufacturing cost of precipitated silica compared to the prior art, while consuming less resources, reducing emissions, and reducing environmental damage.
  • the prior art is required to consume a large amount of inorganic acid, which may cause a large amount of salty acid-containing wastewater to cause environmental pollution and the like.
  • CO 2 can be introduced into the filtrate to produce MHCO 3 from the carbonate M 2 CO 3 in the filtrate, and the cycle is used as a reaction raw material for preparing precipitated SiO 2 .
  • the filtrate can also be concentrated, and then introduced into CO 2 to form a mixture of a saturated solution of hydrogencarbonate MHCO 3 and its crystals, and then the MHCO 3 solid is recovered by filtration, and the filtrate is recycled as a raw material for preparing precipitated SiO 2 .
  • the filtrate can also be concentrated to the filtrate to partially crystallize the carbonate and bicarbonate to obtain a mixture of a saturated solution and a crystal, and then react the mixture with quartz sand to form a soluble silicate M 2 O.nSiO 2 . And CO 2 , the resulting soluble silicate M 2 O.nSiO 2 is used to form a reaction raw material for precipitating SiO 2 .
  • the above three kinds of different treatments for the filtrate can be used to obtain the reaction raw materials.
  • the corresponding treatment methods can be respectively adopted for different production conditions to obtain the best effect.
  • the method of the invention can reduce the production cost of the precipitated silica product by more than 30% compared with the prior art.
  • the M described in the above technical solution is sodium Na or potassium K. Since Na and K are alkali metal elements, many of the corresponding compounds have similar properties, and the same modulus Na 2 O.nSiO 2 It has many similar properties to K 2 O.nSiO 2 . The other physicochemical properties of Na 2 CO 3 and K 2 CO 3 are similar. Therefore, in the analysis below, M is Na for analysis and M. The case of K can be roughly analogized, or can be understood by referring to the corresponding literature, as described in the aforementioned "Production and Application of Silicon Compounds".
  • the sodium silicate which is the main raw material for preparing precipitated silica will be described below.
  • Sodium silicate commonly known as water glass, is called blister base.
  • the molecular formula can be written as: Na 2 O.nSiO 2 , n is the molar ratio of SiO 2 to Na 2 O, often called the modulus, and the general sodium silicate product.
  • the modulus is between 1.0 and 4.0.
  • Sodium silicate is generally prepared by reacting Na 2 CO 3 with high temperature, and its reaction formula is:
  • Na2O.nSiO2 can also react with HCO3-:
  • filtration equipment in principle, filter press filtration, vacuum filtration equipment and other existing filtration equipment can be used, but considering the washing effect, especially the water saving in the washing process and other factors, so the use of diaphragm filter press will better.
  • the washing water can be directly used tap water, or tap water containing a small amount of NH 4 HCO 3 , which is due to the adsorption of hydrated SiO 2 surface, easy to adsorb a large amount of Na + or K + ions, easy to wash with water alone.
  • the effect of washing can be improved by the exchange of NH4+ ions.
  • it may be considered to soak and wash with a small amount of dilute H 2 SO 4 or dilute HCl.
  • it can promote gel aging, and the main aspect is to make the product slightly acidic to meet the needs of rubber and other industries.
  • wash with tap water generally wash to wash water PH value of 6 ⁇ 7. Of course, these processes can all be done in the filter.
  • the filtrate mainly contains Na 2 CO 3 and NaHCO 3 in the final reaction part.
  • the filtrate is reacted with CO 2 to form NaHCO 3 , and the resulting NaHCO 3 solution can be recycled as a raw material for reaction with Na 2 O.nSiO 2 .
  • the Na 2 CO 3 product can also be directly concentrated and recovered, and can be sent to produce Na 2 O.nSiO 2 when it meets the requirements for reaction with quartz sand (mainly water content).
  • the reaction of this concentrate with SiO 2 involves the decomposition of NaHCO 3 only compared to conventional processes:
  • the Na 2 CO 3 produced here is a raw material for preparing sodium silicate, and the generated CO 2 can be used as a reaction raw material for generating NaHCO 3 from Na 2 CO 3 .
  • CO 2 produced by combustion of the fuel can also be recovered synchronously to supplement the loss or deficiency of CO 2 in the process.
  • Another treatment scheme of the filtrate is: firstly, or without concentration (according to the concentration), passing CO 2 , and the formed saturated portion of NaHCO 3 is analyzed from the middle of the solution, and the portion of NaHCO 3 and the remaining NaHCO 3 are recovered by filtration. The solution is recycled back to the precipitation reaction with Na 2 O.nSiO 2 .
  • the precipitation of NaHCO 3 utilizes the solubility difference between the two.
  • the solubility of Na 2 CO 3 and NaHCO 3 is as follows (g/100 g water): temperature 0°C 10 ° C 20 ° C 30 ° C 40 ° C Na 2 CO 3 7.1 12.5 21.5 39.7 49.0 NaHCO 3 6.9 8.1 9.6 11.1 12.7
  • the obtained NaHCO3 can be recovered as a product, or can be thermally decomposed to obtain Na2CO3 and CO2, and the CO2 cycle is used to generate NaHCO3.
  • the thermal decomposition process of NaHCO3 can be referred to the "Inorganic Technology (Part 2)" (Unified Book No. 15063.3244 (K-246)), pp. 351-361, published by the Chemical Industry Press in December 1981.
  • NaHCO3 can also be directly used as a raw material for the production of Na2O.nSiO2.
  • the washing liquid can be mixed with the filtrate, or can be concentrated first, and the reverse osmosis process can be preferentially used for concentration.
  • the concentrated washing liquid recycling process is basically the same as the filtrate.
  • the present invention only uses quartz sand as a raw material, and Na2O.nSiO2, Na2CO3, NaHCO3 and CO2 can be recycled, that is, as long as the loss of part of Na2CO3 or CO2 is timely supplemented, the process can be continuously and stably performed, which not only greatly reduces the number of
  • the manufacturing cost of precipitated silica also greatly reduces the discharge of salt-containing acid-containing wastewater and CO2, and the entire production process, equipment and original manufacturing process are basically unchanged, and the investment of fixed assets is not increased, and the process advantage is very obvious.
  • the cycle using K2O.nSiO2, K2CO3, and KHCO3 is also substantially the same.
  • the process technology of the present invention may comprise a complete process from the above three reactions (processes), or may be selected or not used in addition to the main reaction (process) (1), for example, selecting only (1), (2), that is, after the regeneration or recovery of part of NaHCO3/KHCO3 or Na2CO3/K2CO3, the formation process of sodium silicate/potassium silicate is not performed.
  • process main reaction
  • the process therefore, to better illustrate the process, will be exemplified by the above three reactions (process).
  • the corresponding process the same or similar to the traditional (or current) process, only a brief description will be made here, and the corresponding references are listed as much as possible.
  • sodium silicate was replaced by a similar modulus of potassium silicate, and NaHCO3 was replaced by KHCO3.
  • the similar weight and precipitation were obtained according to the similar amount and molar concentration without changing other conditions and processes.
  • the molar concentration of the filtrate is also substantially the same.
  • the washing, drying and pulverization of the SiO2 aqueous precipitate are carried out according to laboratory instruments, equipment and processes.
  • the washing precipitate can be filtered by a vacuum filter or a filter press, for example, Diaphragm filter press technology has better water-saving effect.
  • the drying process can be static drying such as a box dryer, but after that, it needs to be crushed to the corresponding fineness by a pulverizer.
  • the pulverization process can be pulverized by airflow pulverization or high-speed eddy current pulverizer, or quasi-static micro-grinding pulverization, but better. It is spray-dried and can be sent directly to the package without further pulverization.
  • Example 2 After filtering and filtering out the SiO2 precipitate in Example 1, about 900 g of the filtrate containing Na2CO3 was obtained, and the NaHCO3 content was 3.8% by CO2 reaction, which was basically the same as the concentration of the NaHCO3 solution prepared before the example, and the weight was also added. More than 600g, enough for recycling.
  • Example 2 After filtering and filtering the SiO2 precipitate in Example 2, about 550 g of a filtrate containing Na2CO3 and a portion of NaHCO3 was obtained, which was designated as A, and the wet precipitate containing the liquid was weighed to about 300 g, and the wet precipitate was soaked and filtered for 2 to 3 times with water. Drain as much as possible, and obtain about 270 g of filtrate. The reaction was carried out by passing CO2 to the filtrate. After the completion of the reaction, the NaHCO3 content was determined to be 4.3%, and the solution was recorded as B, and was used.
  • the filtrate A was concentrated to a liquid weight of about 170 g, and NaHCO 3 crystals were precipitated, and filtered, and the precipitated NaHCO 3 crystal was about 21 g, and the saturated solution was about 150 g.
  • the saturated solution is mixed with solution B to obtain about 450 g.
  • the NaHCO3 solution was tested to have a NaHCO3 concentration of 6.1%, which was recycled for the main reaction as a raw material.
  • Example 3 After filtering and filtering the SiO2 precipitate in Example 3, about 770 g of a filtrate containing Na2CO3 and a portion of NaHCO3 was obtained, which was designated as A, and the wet precipitate of the liquid containing solution was about 230 g, and the wet precipitate was soaked and filtered with 2 to 3 times of water. Drain as much as possible, and obtain about 230 g of filtrate.
  • the reaction was carried out by passing CO2 to the filtrate. After the completion of the reaction, the NaHCO3 content was determined to be 5.1%, and the solution was recorded as B, and was used.
  • the filtrate A was concentrated to a liquid weight of about 300 g, and NaHCO 3 crystals were precipitated, and filtered, and the precipitated NaHCO 3 crystal was about 32 g, and the saturated solution was about 270 g.
  • the saturated solution is mixed with solution B to obtain about 500 g.
  • the NaHCO3 solution was tested to have a NaHCO3 concentration of 7.4%, which was recycled for the main reaction as a raw material.
  • Example 4 After filtering and filtering off the SiO2 precipitate in Example 4, Na2CO3 and a small amount were obtained.
  • the filtrate of NaHCO3 was about 1300 g, and it was analyzed to contain about 3.8% of Na2CO3, about 0.4% of NaHCO3, and concentrated to obtain a mixture containing about 63 g of solid and a small amount of water, which was used as a raw material for formation.
  • Example 5 The filtrate containing potassium silicate and potassium hydrogencarbonate obtained after the precipitation of SiO2 was filtered out in Example 5, and Na2CO3/ was recovered according to Examples 7-10.
  • the invention is prepared by reacting Na2CO3/K2CO3 with quartz to obtain Na2O.nSiO2/ K2O.nSiO2 process and current dry process Na2O.nSiO2/
  • the K2O.nSiO2 process is completely consistent. For details, see P21 ⁇ P42 and P106 ⁇ P111.
  • KHCO3 reacts with quartz sand, it needs to be analyzed.
  • the calculated values are 0.63 and 0.69, that is, 0.63 kg Na2CO3 per 1 kg NaHCO3, for every 1 kg.
  • KHCO3 can be analyzed to 0.69 kg K2CO3.
  • the CO2 produced at this time mainly consists of three parts: (1) Na2CO3/ K2CO3 reacts with SiO2 to form CO2; (2) NaHCO3/KHCO3 separates CO2; (3) CO2 produced by fuel combustion. These CO2 are mixed in the furnace gas, the furnace gas is recovered by heat, and after dedusting, CO2 can be directly obtained for NaHCO3/KHCO3 reaction, or CO2 can be recovered by the current complete absorption device for subsequent reaction cycle.

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Abstract

Disclosed is a method for preparing precipitated silica, by reacting using a soluble silicate M2O.nSiO2 and a bicarbonate MHCO3 as raw materials, the mole ratio of M2O.nSiO2 to MHCO3 being 1:2.0-2.3, precipitating SiO2 hydrate, separating the filtrate after filtering, and washing and drying the filter cake to obtain a precipitated silica product. The filtrate mainly comprises carbonate M2CO3 and a small amount of bicarbonate MHCO3, wherein M is an alkali metal element Na or K, and n is the modulus thereof. Since the filtrate mainly comprises carbonate M2CO3 and a small amount of bicarbonate MHCO3, the raw materials for the reaction can be obtained by various treatment methods, and can be recycled, thereby decreasing the manufacturing costs, at the same time reducing consumption of resources, lessening emissions, decreasing damage to the environment, and avoiding the problems in the prior art such as the consumption of a large amount of inorganic acid and environmental pollution.

Description

一种沉淀二氧化硅的制备方法  Preparation method of precipitated silica
技术领域Technical field
本发明涉及一种制取沉淀二氧化硅的方法，属于化工技术领域。 The invention relates to a method for preparing precipitated silica, belonging to the technical field of chemical industry.
背景技术Background technique
沉淀二氧化硅又叫白炭黑、沉淀白炭黑，是一种水合无定形硅酸产品，化学表达式一般为mSiO2 .nH2O，外观为白色高度分散的无定形粉末，少量也有加工成颗粒状作为商品的。不溶于水及大部分酸，能溶于苛性钠和氢氟酸，对其他化学药品稳定，耐高温，高温下不分解、不燃烧，具有很高的电绝缘性、多孔性，内表面积大、有吸水性，无毒。Precipitated silica, also known as white carbon black and precipitated white carbon black, is a hydrated amorphous silicic acid product with a chemical expression of mSiO2. .nH2O, the appearance is a white highly dispersed amorphous powder, and a small amount is also processed into pellets as a commodity. Insoluble in water and most acids, soluble in caustic soda and hydrofluoric acid, stable to other chemicals, high temperature resistant, non-decomposing and non-burning at high temperatures, high electrical insulation, porosity, large internal surface area, It is water-absorbing and non-toxic.
沉淀二氧化硅的用途很广，作为合成橡胶的良好补强剂，其性能等同甚至优于炭黑，其他有用作稠化剂或增稠剂，油漆的消光剂，各种合成树脂和塑料制品的填充剂、改性剂，在造纸行业作填充剂和纸的表面配料，等等。 Precipitated silica has a wide range of uses as a good reinforcing agent for synthetic rubber. Its performance is equal to or better than that of carbon black. Others are used as thickeners or thickeners, matting agents for paints, various synthetic resins and plastic products. Fillers, modifiers, fillers and paper surface ingredients in the paper industry, and more.
关于沉淀二氧化硅的生产，成都科技大学出版社1994年5月发行的《硅化合物的生产与应用》（（川）新登字015号）第216-219页较祥细的介绍了现行的几种主要生产工艺。沉淀二氧化硅主要是通过下述反应制取的：Na2 O .n SiO2 +H2SO4+(nx-1)H2O----->n SiO2 .xH2O ↓ + Na2SO4 Regarding the production of precipitated silica, the production and application of silicon compounds issued by Chengdu University of Science and Technology Press in May 1994 ((chuan) Xindengzi No. 015), page 216-219, introduces the current Several major production processes. Precipitated silica is mainly obtained by the following reaction: Na2 O .n SiO2 +H2SO4+(nx-1)H2O----->n SiO2 .xH2O ↓ + Na2SO4
Na2 O .n SiO2 +2HCl+(nx-1)H2O----->n SiO2 .xH2O ↓ + 2NaCl Na2 O .n SiO2 +2HCl+(nx-1)H2O----->n SiO2 .xH2O ↓ + 2NaCl
所以，无论用哪种方法，除了消耗作为硅源的硅酸钠外，还需消耗一定量的硫酸或盐酸，当用盐析工艺时，另需消耗一定量的氯化钠。Therefore, no matter which method is used, in addition to consuming sodium silicate as a silicon source, a certain amount of sulfuric acid or hydrochloric acid is consumed, and when a salting-out process is used, a certain amount of sodium chloride is additionally consumed.
该书中列出了相应的消耗定额，每生产1吨沉淀二氧化硅，除消耗相应硅酸钠外，还需消耗：The corresponding consumption quota is listed in the book. For each ton of precipitated silica produced, in addition to the consumption of the corresponding sodium silicate, it is also consumed:
溶胶法：30%盐酸：1.5吨；Sol method: 30% hydrochloric acid: 1.5 tons;
酸-盐析法：NaCl：0.275吨； 30%盐酸：1.15吨；Acid-salting method: NaCl: 0.275 tons; 30% hydrochloric acid: 1.15 tons;
凝胶化法：98%硫酸：0.7吨。Gelation method: 98% sulfuric acid: 0.7 tons.
除了相应酸、盐的消耗，另一个不容忽视的问题是，当反应完成后，这些酸会生成相应的无机盐NaCl和Na2SO4，因此，在压滤、洗涤过程中，会产生大量的含盐含酸废水，由于浓度及工艺费用等方面的因素，这些含盐含酸废水回收成本较高，回收物价值又不大，因此不可避免的会排放大量废水。In addition to the consumption of the corresponding acid and salt, another problem that cannot be ignored is that when the reaction is completed, these acids will form the corresponding inorganic salts NaCl and Na2SO4. Therefore, during the filtration and washing process, a large amount of salt-containing content will be produced. Acid wastewater, due to factors such as concentration and process cost, the recovery cost of these salt-containing acid-containing wastewater is relatively high, and the value of the recovered product is not large, so it is inevitable that a large amount of wastewater will be discharged.
由于上述工艺需消耗大量无机酸，产生大量含盐含酸废水无法循环或回收利用，存在生产成本较高，同时引起环境污染等问题。Since the above process consumes a large amount of inorganic acid, a large amount of salt-containing acid-containing wastewater cannot be recycled or recycled, and there are problems such as high production cost and environmental pollution.
发明内容Summary of the invention
针对上述问题，本发明拟解决的问题是提供一种除硅源（可溶性硅酸盐或石英砂）外，其他化学品能循环使用的制取沉淀二氧化硅的方法，以降低沉淀二氧化硅的制造成本，同时少消耗资源，减少排放，尽量减少对环境的损害。In view of the above problems, the problem to be solved by the present invention is to provide a method for preparing precipitated silica which can be recycled by using other chemicals besides a silicon source (soluble silicate or quartz sand) to reduce precipitated silica. Manufacturing costs, while consuming less resources, reducing emissions, and minimizing damage to the environment.
为达到上述目的，本发明采用以下技术方案：一种沉淀二氧化硅的制备方法，它是以可溶性硅酸盐M2O.nSiO2和碳酸氢盐MHCO3为原料，以M2O.nSiO2和MHCO3的摩尔比为1：2.0~2.3进行反应，沉淀出水合SiO2，经过滤分去滤液，滤饼再经洗涤、干燥得到沉淀二氧化硅产品；所述滤液中主要含有碳酸盐M2CO3和少量的碳酸氢盐MHCO3；所述可溶性硅酸盐M2O.nSiO2、碳酸盐M2CO3、碳酸氢盐MHCO3中的M为碱金属元素Na或K，所述可溶性硅酸盐M2O.nSiO2中的n为其模数。In order to achieve the above object, the present invention adopts the following technical scheme: a method for preparing precipitated silica, which is based on soluble silicate M 2 O.nSiO 2 and hydrogencarbonate MHCO 3 as M 2 O.nSiO. The molar ratio of 2 to MHCO 3 is 1:2.0~2.3, the hydrated SiO 2 is precipitated, the filtrate is separated by filtration, and the filter cake is washed and dried to obtain a precipitated silica product; the filtrate mainly contains carbonic acid. Salt M 2 CO 3 and a small amount of hydrogencarbonate MHCO 3 ; M in the soluble silicate M 2 O.nSiO 2 , carbonate M 2 CO 3 , hydrogencarbonate MHCO 3 is alkali metal element Na or K , n in the soluble silicate M 2 O.nSiO 2 is its modulus.
所述可溶性硅酸盐M2O.nSiO2的模数n，当M是碱金属元素Na时，n值在1.0~3.7，当M是碱金属元素K时，n值在于2.2~3.7。The modulus n of the soluble silicate M 2 O.nSiO 2 is such that when M is an alkali metal element Na, the value of n is from 1.0 to 3.7, and when M is an alkali metal element K, the value of n is from 2.2 to 3.7.
所述过滤是采用真空过滤或压滤机过滤。所述干燥采用喷雾干燥、箱式干燥或气流干燥。所述箱式干燥后还进行了粉碎。The filtration is by vacuum filtration or a filter press. The drying is by spray drying, box drying or air drying. The box was also pulverized after drying.
所述滤液中可以通入CO2，使滤液中的碳酸盐M2CO3生成MHCO3，循环作为制备沉淀SiO2的反应原料。The filtrate may be passed with CO 2 to cause the carbonate M 2 CO 3 in the filtrate to form MHCO 3 , which is recycled as a reaction raw material for preparing precipitated SiO 2 .
所述滤液也可以经浓缩后，通入CO2，生成碳酸氢盐MHCO3的饱和溶液与其结晶物的混合物，所述的浓缩是控制在使结晶的MHCO3占混合物中MHCO3的40~45%，然后过滤回收MHCO3固体，滤液作为制备沉淀SiO2的原料循环使用。After the filtrate may be concentrated into CO 2, to produce a mixture of saturated bicarbonate solution thereto MHCO 3 crystals, the concentration is controlled so that the crystallization mixture MHCO 3 accounted for in the MHCO 40 ~ 45 3 %, then MHCO 3 solids were recovered by filtration, and the filtrate was recycled as a raw material for preparing precipitated SiO 2 .
所述滤液还可以经浓缩至滤液中碳酸盐和碳酸氢盐部分结晶，得到饱和溶液与结晶物的混合物，然后将所述混合物与石英砂反应，生成可溶性硅酸盐M2O.nSiO2和CO2，所述生成的可溶性硅酸盐M2O.nSiO2用于生成沉淀SiO2的反应原料，所述的浓缩控制在使混合物的含水量符合生产M2O.nSiO2的工艺要求。The filtrate may also be partially concentrated to a carbonate and a bicarbonate in the filtrate to obtain a mixture of a saturated solution and a crystal, and then the mixture is reacted with quartz sand to form a soluble silicate M 2 O.nSiO 2 . And CO 2 , the produced soluble silicate M 2 O.nSiO 2 is used to generate a reaction raw material for precipitating SiO 2 , and the concentration is controlled so that the water content of the mixture conforms to the process requirement for producing M 2 O.nSiO 2 .
采用上述技术方案，本发明的沉淀二氧化硅的制备方法，它是以可溶性硅酸盐M2O.nSiO2和碳酸氢盐MHCO3为原料，进行反应，沉淀出水合SiO2，干燥得到沉淀二氧化硅产品。由于滤液中主要含有碳酸盐M2CO3和少量的碳酸氢盐MHCO3,滤液中碳酸盐M2CO3和少量的碳酸氢盐MHCO3可以通过不同的处理方式获得反应原料，因此除硅源（可溶性硅酸盐或石英砂）外，其他化学品能循环使用，与现有技术相比，降低了沉淀二氧化硅的制造成本，同时少消耗资源，减少排放，减少对环境的损害。避免了现有技术需消耗大量无机酸，会导致产生大量含盐含酸废水，引起环境污染等问题。According to the above technical solution, the method for preparing precipitated silica of the present invention comprises the steps of: reacting soluble silicate M 2 O.nSiO 2 and hydrogencarbonate MHCO 3 as raw materials, precipitating hydrated SiO 2 , and drying to obtain a precipitate. Silica products. Since the filtrate mainly contains carbonate and a small amount of M 2 CO 3 MHCO 3 bicarbonates, carbonates filtrate M 2 CO 3 and a small amount of bicarbonate MHCO 3 may be obtained by reaction of raw materials of different treatments, so in addition to In addition to silicon sources (soluble silicate or quartz sand), other chemicals can be recycled, reducing the manufacturing cost of precipitated silica compared to the prior art, while consuming less resources, reducing emissions, and reducing environmental damage. . The prior art is required to consume a large amount of inorganic acid, which may cause a large amount of salty acid-containing wastewater to cause environmental pollution and the like.
技术方案中还列举了一些对滤液不同的处理方式获得反应原料：The technical scheme also lists some different treatment methods for the filtrate to obtain the reaction raw materials:
一是滤液中可以通入CO2，使滤液中的碳酸盐M2CO3生成MHCO3，循环作为制备沉淀SiO2的反应原料。First, CO 2 can be introduced into the filtrate to produce MHCO 3 from the carbonate M 2 CO 3 in the filtrate, and the cycle is used as a reaction raw material for preparing precipitated SiO 2 .
二是滤液也可以经浓缩后，通入CO2，生成碳酸氢盐MHCO3的饱和溶液与其结晶物的混合物，然后过滤回收MHCO3固体，滤液作为制备沉淀SiO2的原料循环使用。Second, the filtrate can also be concentrated, and then introduced into CO 2 to form a mixture of a saturated solution of hydrogencarbonate MHCO 3 and its crystals, and then the MHCO 3 solid is recovered by filtration, and the filtrate is recycled as a raw material for preparing precipitated SiO 2 .
三是滤液还可以经浓缩至滤液中碳酸盐和碳酸氢盐部分结晶，得到饱和溶液与结晶物的混合物，然后将所述混合物与石英砂反应，生成可溶性硅酸盐M2O.nSiO2和CO2，所述生成的可溶性硅酸盐M2O.nSiO2用于生成沉淀SiO2的反应原料。Third, the filtrate can also be concentrated to the filtrate to partially crystallize the carbonate and bicarbonate to obtain a mixture of a saturated solution and a crystal, and then react the mixture with quartz sand to form a soluble silicate M 2 O.nSiO 2 . And CO 2 , the resulting soluble silicate M 2 O.nSiO 2 is used to form a reaction raw material for precipitating SiO 2 .
上述三种对滤液不同的处理来获得反应原料，在实际生产中，对不同生产状况可分别采用相应的处理方式，以取得最好的效果。按现行原料价格计算，与现有技术相比，采用本发明方法可降低沉淀二氧化硅产品生产成本30%以上。The above three kinds of different treatments for the filtrate can be used to obtain the reaction raw materials. In the actual production, the corresponding treatment methods can be respectively adopted for different production conditions to obtain the best effect. According to the current raw material price, the method of the invention can reduce the production cost of the precipitated silica product by more than 30% compared with the prior art.
下面对上述技术方案作些简要的分析。The following is a brief analysis of the above technical solutions.
先说一点，上述技术方案中所述的M为钠Na或钾K，由于Na与K同是碱金属元素，二者许多相应的化合物性能都很相近，同模数的Na2O.nSiO2和K2O.nSiO2其许多性能都很相似，其他Na2CO3与K2CO3其物理化学性能也都很相似，所以在下述的分析中主要是以M为Na作分析，对M为K的情形大致依次类推即可，或参考相应文献即可了解，如本专利前述之《硅化合物的生产与应用》。First of all, the M described in the above technical solution is sodium Na or potassium K. Since Na and K are alkali metal elements, many of the corresponding compounds have similar properties, and the same modulus Na 2 O.nSiO 2 It has many similar properties to K 2 O.nSiO 2 . The other physicochemical properties of Na 2 CO 3 and K 2 CO 3 are similar. Therefore, in the analysis below, M is Na for analysis and M. The case of K can be roughly analogized, or can be understood by referring to the corresponding literature, as described in the aforementioned "Production and Application of Silicon Compounds".
下面先介绍下作为制备沉淀二氧化硅的主要原料硅酸钠。The sodium silicate which is the main raw material for preparing precipitated silica will be described below.
硅酸钠，俗名水玻璃，商品名为泡化碱，分子式可写作：Na2O.nSiO2，n为SiO2与Na2O的摩尔比，常称为模数，一般硅酸钠产品的模数在1.0~4.0。Sodium silicate, commonly known as water glass, is called blister base. The molecular formula can be written as: Na 2 O.nSiO 2 , n is the molar ratio of SiO 2 to Na 2 O, often called the modulus, and the general sodium silicate product. The modulus is between 1.0 and 4.0.
硅酸钠一般由Na2CO3与在高温下反应制得，其反应式为：Sodium silicate is generally prepared by reacting Na 2 CO 3 with high temperature, and its reaction formula is:
Na2CO3+ nSiO2== Na2O.nSiO2+CO2 Na 2 CO 3 + nSiO 2 == Na 2 O.nSiO 2 + CO 2
关于制取硅酸钠的工艺过程，前已提及的《硅化合物的生产与应用》第21~42页祥细论述了固相法生产硅酸钠的工艺，这也是本专利用回收的Na2CO3与石英砂（SiO2）反应制取硅酸钠采用的方法，所以这里不再细述。唯一的差异是本专利技术方案中回收的Na2CO3中，会另混有NaHCO3，但NaHCO3在生产初期升温阶段即分解为Na2CO3：Regarding the process of preparing sodium silicate, the above-mentioned "Production and Application of Silicon Compounds", pages 21-42, discusses in detail the process of solid sodium production of sodium silicate, which is also the Na recovered by this patent. 2 CO 3 is reacted with quartz sand (SiO 2 ) to prepare sodium silicate, so it will not be described in detail here. The only difference is Na 2 CO 3 in the present patent aspect recovered, the other will be mixed with NaHCO 3, NaHCO 3, but in the early stage of the production of heating decomposition Na 2 CO 3:
2NaHCO3== Na2CO3 + H2O + CO2 2NaHCO 3 == Na 2 CO 3 + H 2 O + CO 2
所以混有NaHCO3的Na2CO3与SiO2的反应与常规反应无差别，需注意的只是在计算配料时2mol的NaHCO3等效于1mol的Na2CO3，同时在作热量平衡时也需作些相应考虑，即反应所用的燃料比全部用Na2CO3的要稍多。Therefore, the reaction of Na 2 CO 3 mixed with NaHCO 3 with SiO 2 is no different from the conventional reaction. It should be noted that 2 mol of NaHCO 3 is equivalent to 1 mol of Na 2 CO 3 when calculating the ingredients, and also when the heat is balanced. A corresponding consideration needs to be made, that is, the fuel used for the reaction is slightly more than the total amount of Na 2 CO 3 .
硅酸钠极易与酸发生反应析出二氧化硅，前面已写了Na2O.nSiO2与H2SO4和HCl反应的方程式，但实际上，Na2O.nSiO2甚至能与NH4+这样的弱酸（路易斯酸）反应：Sodium silicate is very easy to react with acid to precipitate silica. The equation for the reaction of Na 2 O.nSiO 2 with H 2 SO 4 and HCl has been written before, but in fact, Na 2 O.nSiO 2 can even react with NH 4 . + Such a weak acid (Lewis acid) reaction:
硅酸钠极易与酸发生反应析出二氧化硅，前面已写了 Na2O.nSiO2 与H2SO4和HCl反应的方程式，但实际上， Na2O.nSiO2 甚至能与NH4+这样的弱酸（路易斯酸）反应：Na2 O .n SiO2 +2NH4Cl+(nx-1)H2O----->n SiO2 .xH2O ↓ + 2NaCl +2NH3 Sodium silicate is very easy to react with acid to precipitate silica.2O.nSiO2With H2SO4The equation of reaction with HCl, but in fact, Na2O.nSiO2 Even reacts with a weak acid such as NH4+ (Lewis acid): Na2 O.n SiO2 +2NH4Cl+(nx-1)H2O----->n SiO2 .xH2O ↓ + 2NaCl +2NH3
在这里，NH4+是作为一个酸，可逆反应成NH3和H+（ PKa=9.25）Here, NH 4 + acts as an acid and reversibly reacts into NH 3 and H+ ( PKa = 9.25)
相类似的，Na2O.nSiO2 也能与HCO3-反应：Similarly, Na2O.nSiO2 can also react with HCO3-:
Na2 O .n SiO2 +NH4HCO3+(nx-1)H2O----->n SiO2 .xH2O ↓ + Na2CO3+NH3 Na2 O .n SiO2 +NH4HCO3+(nx-1)H2O----->n SiO2 .xH2O ↓ + Na2CO3+NH3
Na2 O .n SiO2 +2NaHCO3+(nx-1)H2O----->n SiO2 .xH2O ↓ + 2Na2CO3 Na2 O .n SiO2 +2NaHCO3+(nx-1)H2O----->n SiO2 .xH2O ↓ + 2Na2CO3
HCO3- 可逆反应成H+和CO32-(PKa=10.3)HCO3- reversible reaction into H+ and CO 3 2- (PKa = 10.3)
这是本发明的反应原理。This is the reaction principle of the present invention.
当用NaHCO3使Na2O.nSiO2中SiO2析出后，经过滤、洗涤、干燥即可得到沉淀二氧化硅产品，这些工艺过程完全等同于现行沉淀二氧化硅生产工艺，具体可参见《硅化合物的生产与应用》第216-219页相关工艺。另需补充几点： 3 so that when Na 2 O.nSiO 2 in SiO 2 after precipitation with NaHCO, filtered, washed, and dried to obtain precipitated silica products, these processes exactly the same as the existing manufacturing process of precipitated silica, in particular the section " Process for the Production and Application of Silicon Compounds, pp. 216-219. Another point to add:
1，过滤设备：原则上压滤机过滤，真空过滤设备等现有过滤设备均可使用，但考虑到洗涤效果，特别是洗涤过程中的节水等因素，所以使用隔膜式压滤机效果会更好。1, filtration equipment: in principle, filter press filtration, vacuum filtration equipment and other existing filtration equipment can be used, but considering the washing effect, especially the water saving in the washing process and other factors, so the use of diaphragm filter press will better.
2，洗涤用水可直接用自来水，也可用含少量NH4HCO3的自来水，这是由于水合SiO2表面有吸附性，容易吸附大量的Na+或K+离子，单纯用水不易洗净。利用NH4+离子的交换作用可提高洗涤的效果。而后期可考虑用少量稀H2SO4或稀HCl浸泡、洗涤，一方面可以促进凝胶老化，另主要的方面是可以使产品带微酸性，以满足橡胶等行业的需要。然后再用自来水洗涤，一般洗至洗水PH值在6~7即可。当然，这些过程均可在过滤机内完成。2, the washing water can be directly used tap water, or tap water containing a small amount of NH 4 HCO 3 , which is due to the adsorption of hydrated SiO 2 surface, easy to adsorb a large amount of Na + or K + ions, easy to wash with water alone. The effect of washing can be improved by the exchange of NH4+ ions. In the later stage, it may be considered to soak and wash with a small amount of dilute H 2 SO 4 or dilute HCl. On the one hand, it can promote gel aging, and the main aspect is to make the product slightly acidic to meet the needs of rubber and other industries. Then wash with tap water, generally wash to wash water PH value of 6~7. Of course, these processes can all be done in the filter.
3，当过滤分去含SiO2沉淀后，滤液主要含Na2CO3和末反应部分的NaHCO3，这时可有多种方案回收这些Na2CO3和NaHCO3供重复循环使用，如可在滤液中通CO2反应生成NaHCO3，生成的NaHCO3溶液可作为与Na2O.nSiO2反应的原料循环使用。也可直接浓缩回收Na2CO3产品，至能符合与石英砂反应的要求（主要是含水量）时送去生产Na2O.nSiO2。只与常规工艺相比，这个浓缩液与SiO2反应会涉及到NaHCO3的分解：3. When the SiO 2 precipitate is separated by filtration, the filtrate mainly contains Na 2 CO 3 and NaHCO 3 in the final reaction part. At this time, there are various schemes for recovering these Na 2 CO 3 and NaHCO 3 for repeated recycling, such as The filtrate is reacted with CO 2 to form NaHCO 3 , and the resulting NaHCO 3 solution can be recycled as a raw material for reaction with Na 2 O.nSiO 2 . The Na 2 CO 3 product can also be directly concentrated and recovered, and can be sent to produce Na 2 O.nSiO 2 when it meets the requirements for reaction with quartz sand (mainly water content). The reaction of this concentrate with SiO 2 involves the decomposition of NaHCO 3 only compared to conventional processes:
2NaHCO3 =Na2CO3 +H2O+ CO2 2NaHCO 3 =Na 2 CO 3 +H 2 O+ CO 2
这里生成的Na2CO3即是制备硅酸钠的原料，生成的CO2可用于由Na2CO3生成NaHCO3 的反应原料。另外，在由Na2CO3制取硅酸钠时，由燃料燃烧产生的CO2也可同步回收，以补充过程中CO2的损耗或不足。The Na 2 CO 3 produced here is a raw material for preparing sodium silicate, and the generated CO 2 can be used as a reaction raw material for generating NaHCO 3 from Na 2 CO 3 . In addition, when sodium silicate is prepared from Na 2 CO 3 , CO 2 produced by combustion of the fuel can also be recovered synchronously to supplement the loss or deficiency of CO 2 in the process.
滤液的另一种处理方案是：先初步浓缩，或不经浓缩（根据浓度），通入CO2，使生成的NaHCO3饱和部分从溶液中部分析出，过滤回收析出部分NaHCO3 ，余NaHCO3 溶液循环回用于与Na2O.nSiO2的沉淀反应。NaHCO3的析出是利用了二者的溶解度差。Na2CO3与NaHCO3 的溶解度比较如下（g/100g水）：
温度 0℃ 10℃ 20℃ 30℃ 40℃
Na2CO3 7.1 12.5 21.5 39.7 49.0
NaHCO3 6.9 8.1 9.6 11.1 12.7
Another treatment scheme of the filtrate is: firstly, or without concentration (according to the concentration), passing CO 2 , and the formed saturated portion of NaHCO 3 is analyzed from the middle of the solution, and the portion of NaHCO 3 and the remaining NaHCO 3 are recovered by filtration. The solution is recycled back to the precipitation reaction with Na 2 O.nSiO 2 . The precipitation of NaHCO 3 utilizes the solubility difference between the two. The solubility of Na 2 CO 3 and NaHCO 3 is as follows (g/100 g water):
temperature 0°C 10 ° C 20 ° C 30 ° C 40 ° C
Na 2 CO 3 7.1 12.5 21.5 39.7 49.0
NaHCO 3 6.9 8.1 9.6 11.1 12.7
在常温（20℃~30℃左右）能利用Na2CO3与NaHCO3的溶解度差使NaHCO3从溶液中析出，这样可简化回收NaHCO3的工艺过程。At normal temperature (about 20 ° C ~ 30 ° C), the solubility of Na2CO3 and NaHCO3 can be used to precipitate NaHCO3 from the solution, which simplifies the process of recovering NaHCO3.
得到的NaHCO3可作为产品回收，也可热分解得到Na2CO3和CO2，CO2循环用于生成NaHCO3。NaHCO3热分解工艺可参考化学工业出版社会学1981年12月出版的《无机物工艺学（下）》（统一书号15063.3244(K-246)）第351-361页相关内容。NaHCO3也可直接用作生产Na2O.nSiO2的原料。The obtained NaHCO3 can be recovered as a product, or can be thermally decomposed to obtain Na2CO3 and CO2, and the CO2 cycle is used to generate NaHCO3. The thermal decomposition process of NaHCO3 can be referred to the "Inorganic Technology (Part 2)" (Unified Book No. 15063.3244 (K-246)), pp. 351-361, published by the Chemical Industry Press in December 1981. NaHCO3 can also be directly used as a raw material for the production of Na2O.nSiO2.
4，再补充一点，滤饼的洗涤液中也可回收Na2CO3和NaHCO3，特别是前期的洗液，这样可进一步减少循环原料的损耗和废液的排放。洗涤液可与滤液混合使用，也可先经浓缩，浓缩可优先使用反渗透工艺，浓缩后的洗液循环回用工艺与滤液的基本一致。4, add a little more, Na2CO3 and NaHCO3 can be recovered in the washing liquid of the filter cake, especially the previous washing liquid, which can further reduce the loss of circulating raw materials and the discharge of waste liquid. The washing liquid can be mixed with the filtrate, or can be concentrated first, and the reverse osmosis process can be preferentially used for concentration. The concentrated washing liquid recycling process is basically the same as the filtrate.
根据以上说明可知，本发明仅以石英砂为原料，Na2O.nSiO2、Na2CO3、NaHCO3和CO2均可循环使用，即只要适时补充部分Na2CO3或CO2的损耗即可使工艺连续稳定进行，不仅大大减少了沉淀二氧化硅的制造成本，也大幅减少了含盐含酸废水和CO2的排放，而且整个生产工艺、设备与原制造工艺基本未变，不会增加固定资产的投入，工艺优势十分明显。 According to the above description, the present invention only uses quartz sand as a raw material, and Na2O.nSiO2, Na2CO3, NaHCO3 and CO2 can be recycled, that is, as long as the loss of part of Na2CO3 or CO2 is timely supplemented, the process can be continuously and stably performed, which not only greatly reduces the number of The manufacturing cost of precipitated silica also greatly reduces the discharge of salt-containing acid-containing wastewater and CO2, and the entire production process, equipment and original manufacturing process are basically unchanged, and the investment of fixed assets is not increased, and the process advantage is very obvious.
使用K2O.nSiO2、K2CO3、KHCO3的循环也基本相同。The cycle using K2O.nSiO2, K2CO3, and KHCO3 is also substantially the same.
具体实施方式 detailed description
从前面的说明可知，本发明制取沉淀二氧化硅工艺大致可按下述三个反应（过程）串联配合组成：As can be seen from the foregoing description, the process for preparing precipitated silica of the present invention can be roughly combined in the following three reaction (process) series:
（1）主反应：由Na2O.nSiO2/ K2O.nSiO2与相应碳酸氢盐反应得到水合SiO2凝胶（或沉淀），然后经过滤、洗涤、干燥、（粉碎）、包装得到沉淀二氧化硅产品。(1) Main reaction: from Na2O.nSiO2/ K2O.nSiO2 is reacted with the corresponding bicarbonate to obtain a hydrated SiO2 gel (or precipitate), which is then filtered, washed, dried, (pulverized), and packaged to obtain a precipitated silica product.
（2）主反应后过滤滤液的处理；(2) treatment of filtering the filtrate after the main reaction;
（3）石英砂与Na2CO3/ K2CO3反应生成Na2O.nSiO2/ K2O.nSiO2的反应。(3) The reaction of quartz sand with Na2CO3/K2CO3 to form Na2O.nSiO2/K2O.nSiO2.
本发明工艺技术可以由上述三个反应（过程）组成一个完整的工艺过程，也可以除主反应（过程）（1）之外，对辅助反应（过程）选择用或不用，例如，选择只进行（1）、（2），即在再生、回收部分NaHCO3/KHCO3或Na2CO3/K2CO3后，不再进行硅酸钠/硅酸钾的生成过程。另，在同一个反应过程中可能有多种实施方式，而在实际生产中，可据生产实际选择其中一种生产工艺，然后与另一个过程中的某一个组合，即可组成一个完整的工艺过程，所以，为更好的说明其工艺过程，将以上述三个反应（过程）分别举例说明。另说明一下，对相应工艺，与传统（或现行）工艺相同或相似的，这里将只作简单的说明，并尽量列出相应参考文献。The process technology of the present invention may comprise a complete process from the above three reactions (processes), or may be selected or not used in addition to the main reaction (process) (1), for example, selecting only (1), (2), that is, after the regeneration or recovery of part of NaHCO3/KHCO3 or Na2CO3/K2CO3, the formation process of sodium silicate/potassium silicate is not performed. In addition, there may be multiple implementations in the same reaction process, and in actual production, one of the production processes can be selected according to the actual production, and then combined with one of the other processes to form a complete process. The process, therefore, to better illustrate the process, will be exemplified by the above three reactions (process). In addition, for the corresponding process, the same or similar to the traditional (or current) process, only a brief description will be made here, and the corresponding references are listed as much as possible.
（一）主反应(a) the main reaction
实施例1Example 1
取一种波美度为37°Be’（20℃，下同）的硅酸钠，加入4倍量（重量，下同）的水稀释、过滤，测得稀释液含SiO2%=5.0%，Na2O%=1.4%，其模数n=3.7，称取该稀溶液600g，在搅拌下与600g 3.8%的NaHCO3溶液混合(反应摩尔比为1:2.0)，至检验液相中基本无SiO2，继续搅拌约20分钟，过滤，用清水洗涤沉淀，至洗水近中性，沥干，在烘箱中干燥，再粉碎，可得到成品沉淀二氧化硅约27.5g。Take a sodium silicate with a Baume degree of 37 ° Be' (20 ° C, the same below), add 4 times the amount (weight, the same below) of water to dilute and filter, and measure the dilution containing SiO2%=5.0%. Na2O%=1.4%, its modulus n=3.7, weigh 600g of the dilute solution, with stirring and 600g 3.8% NaHCO3 solution was mixed (reaction molar ratio 1:2.0), until the test liquid phase was substantially free of SiO2, stirring was continued for about 20 minutes, filtered, and the precipitate was washed with water until the wash was near neutral, drained, in an oven The mixture was dried and pulverized to obtain about 27.5 g of the finished precipitated silica.
实施例2Example 2
取一种波美度为40°Be′的硅酸钠，加入3倍量的水稀释、过滤，测得稀释液含SiO2%=7.3%，Na2O%=2.3%，其模数n=3.3，称取该稀硅酸钠溶液400g，在搅拌下与450g含6.1%的NaHCO3溶液混合(反应摩尔比为1:2.2)，至检验液相中基本无SiO2，继续搅拌约20分钟，过滤，用清水洗涤沉淀，至洗水近中性，沥干，在烘箱中干燥，再粉碎，可得到成品沉淀二氧化硅约28.0g。Take a sodium silicate with a Baume degree of 40°Be', dilute and filter with 3 times of water, and measure the dilution containing SiO2%=7.3%, Na2O%=2.3%, and its modulus n=3.3. Weigh 400g of the dilute sodium silicate solution, mix with 450g of 6.1% NaHCO3 solution under stirring (reaction molar ratio 1:2.2), until the test liquid phase is substantially SiO2 free, continue stirring for about 20 minutes, filter, use The precipitate was washed with water, until the washing water was nearly neutral, drained, dried in an oven, and pulverized to obtain about 28.0 g of the finished precipitated silica.
实施例3Example 3
取一种波美度为50°Be′的硅酸钠，加入4倍量的水稀释、过滤，测得稀释液含SiO2%=5.8%，Na2O%=2.6%，其模数n=2.3，称取该种稀硅酸钠溶液500g，在搅拌下与500g含7.4%的NaHCO3溶液混合(反应摩尔比为1:2.1)，至检验液相中基本无SiO2，继续搅拌约20分钟，过滤，用清水洗涤沉淀，至洗水近中性，沥干，在烘箱中干燥，再粉碎，可得到成品沉淀二氧化硅约27.5g。Take a sodium silicate with a Baume degree of 50°Be', dilute and filter with 4 times the amount of water, and measure the dilution containing SiO2%=5.8%, Na2O%=2.6%, and its modulus n=2.3. Weigh 500g of this kind of dilute sodium silicate solution, mix with 500g of 7.4% NaHCO3 solution under stirring (reaction molar ratio is 1:2.1), until the test liquid phase is basically no SiO2, continue stirring for about 20 minutes, and filter. The precipitate was washed with water until the washing water was nearly neutral, drained, dried in an oven, and pulverized to obtain about 27.5 g of the finished precipitated silica.
实施例4Example 4
取一种偏硅酸钠Na2SiO3.9H2O产品，加水溶解、过滤，测得其SiO2%=3.1%，Na2O%=3.2%，其模数n=1.0，称取该种溶液600g，在搅拌下与900g含6.6%的NaHCO3溶液混合(反应摩尔比为1:2.3)，至检验液相中基本无SiO2，继续搅拌约20分钟，过滤，用清水洗涤沉淀，至洗水近中性，沥干，在烘箱中干燥，再粉碎，可得到成品沉淀二氧化硅约17g。Take a sodium metasilicate sodium Na2SiO3.9H2O product, dissolve it with water, filter it, and measure its SiO2%=3.1%, Na2O%=3.2%, its modulus n=1.0, weigh 600g of this solution, under stirring 900g containing 6.6% NaHCO3 solution mixed (reaction molar ratio 1:2.3), until the test liquid phase is basically no SiO2, continue to stir for about 20 minutes, filter, wash the precipitate with water, until the wash water is near neutral, drain, Drying in an oven and pulverizing to obtain about 17 g of the finished precipitated silica.
实施例5Example 5
按实施例1~3，用相近模数的硅酸钾代换硅酸钠，用KHCO3代换NaHCO3，按相近的量和摩尔浓度，不改变其他条件和工艺过程，同样可得到相似重量的沉淀二氧化硅产品，滤液的摩尔浓度也基本一致。According to the examples 1 to 3, sodium silicate was replaced by a similar modulus of potassium silicate, and NaHCO3 was replaced by KHCO3. The similar weight and precipitation were obtained according to the similar amount and molar concentration without changing other conditions and processes. For silica products, the molar concentration of the filtrate is also substantially the same.
实施例6Example 6
按实施例1~5，在用洗水洗涤沉淀后，用0.01~0.1 M的稀H2SO4或稀HCl洗涤SiO2沉淀几遍，沥干老化后用少量清水洗净，再去干燥、粉碎，也可得到沉淀二氧化硅产品。According to the examples 1 to 5, after washing the precipitate with washing water, use 0.01~0.1 The SiO2 precipitate is washed several times with dilute H2SO4 or dilute HCl of M. After draining and aging, it is washed with a small amount of water, and then dried and pulverized to obtain a precipitated silica product.
在实施例1~6中，SiO2含水沉淀的洗涤、干燥、粉碎均是按实验室的仪器、设备和过程进行的，在实际生产中，洗涤沉淀可以用真空过滤或压滤机过滤，例如用隔膜压滤技术洗涤节水效果较好。干燥过程可采用静态干燥如厢式干燥器，但这样之后需采用粉碎机粉碎至相应细度，粉碎过程可以用气流粉碎或高速涡流粉碎机粉碎，也可以准静态微粉磨粉碎，但更好的是采用喷雾干燥，可不再进行粉碎直接送去包装。In Examples 1 to 6, the washing, drying and pulverization of the SiO2 aqueous precipitate are carried out according to laboratory instruments, equipment and processes. In actual production, the washing precipitate can be filtered by a vacuum filter or a filter press, for example, Diaphragm filter press technology has better water-saving effect. The drying process can be static drying such as a box dryer, but after that, it needs to be crushed to the corresponding fineness by a pulverizer. The pulverization process can be pulverized by airflow pulverization or high-speed eddy current pulverizer, or quasi-static micro-grinding pulverization, but better. It is spray-dried and can be sent directly to the package without further pulverization.
（二）辅助反应（过程）：滤液的回用(2) Auxiliary reaction (process): reuse of filtrate
实施例7 Example 7
在实施例1过滤滤出SiO2沉淀后，得到含Na2CO3的滤液约900g，通CO2反应，检测NaHCO3含量为3.8%，基本上与该实施例前配制的NaHCO3溶液浓度一致，重量也比原加入的600g多，足以循环使用。After filtering and filtering out the SiO2 precipitate in Example 1, about 900 g of the filtrate containing Na2CO3 was obtained, and the NaHCO3 content was 3.8% by CO2 reaction, which was basically the same as the concentration of the NaHCO3 solution prepared before the example, and the weight was also added. More than 600g, enough for recycling.
实施例8Example 8
在实施例2过滤滤去SiO2沉淀后，得到含Na2CO3和部分NaHCO3的滤液约550g，记作A，称量含液的湿沉淀约为300g，用清水分2~3次浸泡湿沉淀、过滤，尽量沥干，又得到滤液约270g，往该滤液中通CO2反应，反应完成后检测其中NaHCO3含量为4.3%，记该溶液为B，备用。After filtering and filtering the SiO2 precipitate in Example 2, about 550 g of a filtrate containing Na2CO3 and a portion of NaHCO3 was obtained, which was designated as A, and the wet precipitate containing the liquid was weighed to about 300 g, and the wet precipitate was soaked and filtered for 2 to 3 times with water. Drain as much as possible, and obtain about 270 g of filtrate. The reaction was carried out by passing CO2 to the filtrate. After the completion of the reaction, the NaHCO3 content was determined to be 4.3%, and the solution was recorded as B, and was used.
对滤液A进行浓缩，至液重约170g，有NaHCO3晶体析出，过滤，称量析出的NaHCO3晶体约为21g，饱和溶液约150g。该饱和溶液与溶液B混合，得到约450g NaHCO3溶液，检测其NaHCO3浓度为6.1% ,可循环用于主反应作原料用。The filtrate A was concentrated to a liquid weight of about 170 g, and NaHCO 3 crystals were precipitated, and filtered, and the precipitated NaHCO 3 crystal was about 21 g, and the saturated solution was about 150 g. The saturated solution is mixed with solution B to obtain about 450 g. The NaHCO3 solution was tested to have a NaHCO3 concentration of 6.1%, which was recycled for the main reaction as a raw material.
实施例9Example 9
在实施例3过滤滤去SiO2沉淀后，得到含Na2CO3和部分NaHCO3的滤液约770g，记作A，称量含液的湿沉淀约为230g，用清水分2~3次浸泡湿沉淀、过滤，尽量沥干，又得到滤液约230g，往该滤液中通CO2反应，反应完成后检测其中NaHCO3含量为5.1%，记该溶液为B，备用。 After filtering and filtering the SiO2 precipitate in Example 3, about 770 g of a filtrate containing Na2CO3 and a portion of NaHCO3 was obtained, which was designated as A, and the wet precipitate of the liquid containing solution was about 230 g, and the wet precipitate was soaked and filtered with 2 to 3 times of water. Drain as much as possible, and obtain about 230 g of filtrate. The reaction was carried out by passing CO2 to the filtrate. After the completion of the reaction, the NaHCO3 content was determined to be 5.1%, and the solution was recorded as B, and was used.
对滤液A进行浓缩，至液重约300g，有NaHCO3晶体析出，过滤，称量析出的NaHCO3晶体约为32g，饱和溶液约270g。该饱和溶液与溶液B混合，得到约500g NaHCO3溶液，检测其NaHCO3浓度为7.4% ,可循环用于主反应作原料用。 The filtrate A was concentrated to a liquid weight of about 300 g, and NaHCO 3 crystals were precipitated, and filtered, and the precipitated NaHCO 3 crystal was about 32 g, and the saturated solution was about 270 g. The saturated solution is mixed with solution B to obtain about 500 g. The NaHCO3 solution was tested to have a NaHCO3 concentration of 7.4%, which was recycled for the main reaction as a raw material.
实施例10Example 10
在实施例4过滤滤去SiO2沉淀后，得到含Na2CO3和少量 NaHCO3的滤液约1300g，分析其中含Na2CO3约3.8%，NaHCO3约0.4%，浓缩得到含约63 g固体和少量水的混合物，可作生成 的原料。 After filtering and filtering off the SiO2 precipitate in Example 4, Na2CO3 and a small amount were obtained. The filtrate of NaHCO3 was about 1300 g, and it was analyzed to contain about 3.8% of Na2CO3, about 0.4% of NaHCO3, and concentrated to obtain a mixture containing about 63 g of solid and a small amount of water, which was used as a raw material for formation.
对实施例5滤去SiO2沉淀后得到的含硅酸钾、碳酸氢钾的滤液，按与实施例7~10回收Na2CO3/ NaHCO3的相同工艺，过程情况基本一致，只在浓缩时需根据不同温度下KHCO3的溶解度对浓缩量的控制作相应调整。 The filtrate containing potassium silicate and potassium hydrogencarbonate obtained after the precipitation of SiO2 was filtered out in Example 5, and Na2CO3/ was recovered according to Examples 7-10. The same process of NaHCO3, the process is basically the same, only in the concentration should be adjusted according to the solubility of KHCO3 at different temperatures.
（三）辅助反应（过程）：硅酸钠、硅酸钾的再生(3) Auxiliary reaction (process): regeneration of sodium silicate and potassium silicate
本发明由Na2CO3/ K2CO3与石英反应制得Na2O.nSiO2/ K2O.nSiO2过程与现行干法制Na2O.nSiO2/ K2O.nSiO2工艺完全一致，具体可参见《硅化合物的生产与应用》P21~P42和P106~P111。只是由回收的NaHCO3/ KHCO3与石英砂反应时需进行析算，析算值分别为：0.63和0.69，即每1 kg NaHCO3可析算为0.63 kg Na2CO3，每1 kg KHCO3可析算为0.69 kg K2CO3。 The invention is prepared by reacting Na2CO3/K2CO3 with quartz to obtain Na2O.nSiO2/ K2O.nSiO2 process and current dry process Na2O.nSiO2/ The K2O.nSiO2 process is completely consistent. For details, see P21~P42 and P106~P111. Just by recycling NaHCO3/ When KHCO3 reacts with quartz sand, it needs to be analyzed. The calculated values are 0.63 and 0.69, that is, 0.63 kg Na2CO3 per 1 kg NaHCO3, for every 1 kg. KHCO3 can be analyzed to 0.69 kg K2CO3.
用回收的NaHCO3/ KHCO3替代Na2CO3/ K2CO3，不足部分需补充新的Na2CO3和 K2CO3。这里的另一个问题是，这时生成的CO2量会增加：Replacing Na2CO3/K2CO3 with recycled NaHCO3/KHCO3, the new part needs to be supplemented with new Na2CO3 and K2CO3. Another problem here is that the amount of CO2 generated at this time will increase:
2NaHCO3 = Na2CO3+ H2O+ CO2 2NaHCO3 = Na2CO3+ H2O+ CO2
2KHCO3 = K2CO3+ H2O+ CO2 2KHCO3 = K2CO3+ H2O+ CO2
所以，这时产生的CO2主要会有三个部分组成：（1）Na2CO3/ K2CO3与SiO2反应生成CO2；（2）NaHCO3/KHCO3分解放出CO2；（3）燃料燃烧产生的CO2。这些CO2混杂在炉气中，炉气经热量回收，再经除尘后可直接得到CO2供生成NaHCO3/KHCO3反应用，或用现行成套吸收装置回收CO2，供后续反应循环使用。 Therefore, the CO2 produced at this time mainly consists of three parts: (1) Na2CO3/ K2CO3 reacts with SiO2 to form CO2; (2) NaHCO3/KHCO3 separates CO2; (3) CO2 produced by fuel combustion. These CO2 are mixed in the furnace gas, the furnace gas is recovered by heat, and after dedusting, CO2 can be directly obtained for NaHCO3/KHCO3 reaction, or CO2 can be recovered by the current complete absorption device for subsequent reaction cycle.

Claims (8)

  1. 一种沉淀二氧化硅的制备方法，其特征在于它是以可溶性硅酸盐M2O.nSiO2和碳酸氢盐MHCO3为原料，以M2O.nSiO2和MHCO3的摩尔比为1：2.0~2.3进行反应，沉淀出水合SiO2，经过滤分去滤液，滤饼再经洗涤、干燥得到沉淀二氧化硅产品；所述滤液中主要含有碳酸盐M2CO3和少量的碳酸氢盐MHCO3；所述可溶性硅酸盐M2O.nSiO2、碳酸氢盐MHCO3 、碳酸盐M2CO3中的M为碱金属元素Na或K，所述可溶性硅酸盐M2O.nSiO2中的n为其模数。 The invention relates to a method for preparing precipitated silica, which is characterized in that the soluble silicate M2O.nSiO2 and the hydrogencarbonate MHCO3 are used as raw materials, and the molar ratio of M2O.nSiO2 and MHCO3 is 1:2.0~2.3, and the precipitate is precipitated. The SiO2 is hydrated, the filtrate is separated by filtration, and the filter cake is washed and dried to obtain a precipitated silica product; the filtrate mainly contains carbonate M2CO3 and a small amount of hydrogencarbonate MHCO3; the soluble silicate M2O. nSiO2, bicarbonate MHCO3 M in the carbonate M2CO3 is an alkali metal element Na or K, and n in the soluble silicate M2O.nSiO2 is a modulus thereof.
  2. 根据权利要求1所述的沉淀二氧化硅的制备方法，其特征在于所述可溶性硅酸盐M2O.nSiO2的模数n，当M是碱金属元素Na时，n值在1.0~3.7，当M是碱金属元素K时，n值在于2.2~3.7。The method for preparing precipitated silica according to claim 1, characterized in that the modulus n of the soluble silicate M2O.nSiO2, when M is an alkali metal element Na, the value of n is from 1.0 to 3.7, when M When it is an alkali metal element K, the value of n is 2.2 to 3.7.
  3. 根据权利要求1或2所述的沉淀二氧化硅的制备方法，其特征在于所述过滤是采用真空过滤或压滤机过滤。The method for producing precipitated silica according to claim 1 or 2, wherein the filtration is carried out by vacuum filtration or a filter press.
  4. 根据权利要求1或2所述的沉淀二氧化硅的制备方法，其特征在于所述干燥采用喷雾干燥、箱式干燥或气流干燥。The method for producing precipitated silica according to claim 1 or 2, wherein the drying is spray drying, box drying or air flow drying.
  5. 根据权利要求4所述的沉淀二氧化硅的制备方法，其特征在于所述箱式干燥后还进行了粉碎。The method for producing precipitated silica according to claim 4, characterized in that the box is further pulverized after drying.
  6. 根据权利要求1或2所述的沉淀二氧化硅的制备方法，其特征在于所述滤液中通入CO2，使滤液中的碳酸盐M2CO3生成MHCO3，循环作为制备沉淀SiO2的反应原料。The method for preparing precipitated silica according to claim 1 or 2, wherein the filtrate is passed with CO2, and the carbonate M2CO3 in the filtrate is formed into MHCO3, which is recycled as a reaction raw material for preparing precipitated SiO2.
  7. 根据权利要求1或2所述的沉淀二氧化硅的制备方法，其特征在于所述滤液经浓缩后，通入CO2，生成碳酸氢盐MHCO3的饱和溶液与其结晶物的混合物，然后过滤回收MHCO3固体，滤液作为制备沉淀SiO2的原料循环使用；所述的浓缩是控制在使结晶的MHCO3占混合物中MHCO3的40~45%。The method for preparing precipitated silica according to claim 1 or 2, wherein the filtrate is concentrated, and then introduced into CO2 to form a mixture of a saturated solution of hydrogencarbonate MHCO3 and its crystal, and then filtered to recover MHCO3 solid. The filtrate is recycled as a raw material for preparing precipitated SiO2; the concentration is controlled so that the crystallized MHCO3 accounts for 40 to 45% of the MHCO3 in the mixture.
  8. 根据权利要求1或2所述的沉淀二氧化硅的制备方法，其特征在于所述滤液经浓缩至滤液中碳酸盐和碳酸氢盐部分结晶，得到饱和溶液与结晶物的混合物，然后将所述混合物与石英砂反应，生成可溶性硅酸盐M2O.nSiO2和CO2，所述生成的可溶性硅酸盐M2O.nSiO2用于生成沉淀SiO2的反应原料，所述的浓缩控制在使混合物的含水量符合生产M2O.nSiO2的工艺要求。The method for preparing precipitated silica according to claim 1 or 2, wherein the filtrate is concentrated to a portion of the filtrate, wherein the carbonate and the hydrogencarbonate are partially crystallized to obtain a mixture of a saturated solution and a crystal, and then the mixture is The mixture reacts with quartz sand to form soluble silicates M2O.nSiO2 and CO2, and the resulting soluble silicate M2O.nSiO2 is used to form a reaction raw material for precipitating SiO2, and the concentration is controlled to match the water content of the mixture. Process requirements for the production of M2O.nSiO2.
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CN114380296A (en) * 2021-12-29 2022-04-22 四川马边龙泰磷电有限责任公司 Method and device for producing precipitated white carbon black and formate
CN114380296B (en) * 2021-12-29 2023-09-08 四川马边龙泰磷电有限责任公司 Method and device for producing precipitated white carbon black and formate

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