WO1997045368A1 - Procede pour produire une solution de silicate de metal alcalin - Google Patents

Procede pour produire une solution de silicate de metal alcalin Download PDF

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Publication number
WO1997045368A1
WO1997045368A1 PCT/EP1997/002946 EP9702946W WO9745368A1 WO 1997045368 A1 WO1997045368 A1 WO 1997045368A1 EP 9702946 W EP9702946 W EP 9702946W WO 9745368 A1 WO9745368 A1 WO 9745368A1
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WO
WIPO (PCT)
Prior art keywords
silicate solution
bag filter
alkali metal
filter dust
dust
Prior art date
Application number
PCT/EP1997/002946
Other languages
English (en)
Inventor
Jakob Van Rouendal Smit
Original Assignee
Consolidated Metallurgical Industries Limited
Sciarone, Marcel
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from ZA9604301A external-priority patent/ZA964301B/xx
Application filed by Consolidated Metallurgical Industries Limited, Sciarone, Marcel filed Critical Consolidated Metallurgical Industries Limited
Priority to AU32557/97A priority Critical patent/AU3255797A/en
Publication of WO1997045368A1 publication Critical patent/WO1997045368A1/fr

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Classifications

    • 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
    • C01B33/20—Silicates
    • C01B33/32—Alkali metal silicates

Definitions

  • This invention relates to a process for the production of alkali metal silicate solution.
  • the invention has particular application to the production of sodium silicate solution (hereinafter also referred to as SSS) and potassium silicate solution (hereinafter also referred to as KSS).
  • SSS sodium silicate solution
  • KSS potassium silicate solution
  • SSS and KSS are usually produced by fusing together soda ash or potassium carbonate and silica sand at 1200 - 1400°C, followed by digestion of the product in autoclaves with steam to bring the silicate into solution. It is clear that such process is highly energy intensive and uherefore expensive.
  • South African Patent number 87/5531 issued to Phosphate Development Corporation Limited, describes a process for die production of SSS of a dissolved solids content of up to 40% (m/v). This process comprises reacting an aqueous solution of caustic soda with the bag filter dust produced as a low bulk-density waste product in a process for the production of elemental silicon.
  • This byproduct dust is quoted as having a particle size of 71% ⁇ l,5 ⁇ , a SiO 2 content of about 95% and an elemental carbon content of about 2,5%.
  • the bag filter dust which may be converted into a slurry of about 60 per cent by weight with water, is mixed with (further) water and caustic soda, either as a 50 percent (m/v) solution or as NaOH flakes, and the mixture agitated for a number of hours to produce the desired product.
  • an SSS may be produced having a SiOv.NajO ratio of between 1:1 and 4:1 and a total dissolved solids content (i.e. sum of dissolved SiO 2 and Na 2 0 contents) of up to 40%.
  • bag filter dust of a silicon production plant previously disposed of into a slimes dam, and which has been converted into porous lumps through contact with the slurrying water, and cycles of wetting by rain water and drying is also suitable for the production of SSS by the disclosed process, e.g. after crushing the lumps to a fineness of 95% minus 2 mm.
  • This material it is claimed, is only slightly less reactive than the freshly produced bag filter dust in its reaction with NaOH solution.
  • Another source of bag filter dust suitable for the production of SSS with caustic soda is provided by plants producing ferrosilicon.
  • This type of dust has a similar composition and physical properties to that from a silicon smelter, except that it generally contains more metallic oxide (largely iron oxide) impurities, and a somewhat lower percentage, of between about 86 and 92 percent, of silica soluble in a NaOH solution under process conditions similar to those of South African Patent No 87/5531.
  • Such a process is disclosed in German Offenlegungsschrift 26 19 604.
  • an alkali metal silicate solution comprising providing a reaction medium of a bag filter dust from the silicon or ferrometallurgical industry having an alkali-soluble free silica content of at least eighty per cent by mass, and an alkali metal hydroxide and water, reacting, with agitation, the bag filter dust and the hydroxide, and maintaining the temperature of the reaction medium above 70 °C by supplying external heat thereto until the reaction is substantially complete.
  • the temperamre of the reaction mixture is raised to, and maintained at, above 80 ⁇ C, for example at between 80 and 95 °C, for at least 20 minutes after the frothing which occurs in the reaction has subsided.
  • the SSS may have a Si0 2 :Na 2 O ratio of from 2:1 to 4:1, preferably of from 2:1 to 3,5:1, more preferably of about 3,3:1.
  • the total dissolved solids content of the SSS may be from 40 to 75 percent, preferably from 45 to 70 percent, for example from 50 to 65 percent.
  • the KSS may have a molar ratio of from 2: 1 to 4:1, preferably from 2:1 to 3,5:1, more preferably from 2:1 to 3,3:1.
  • the total dissolved solids content of the KSS may be from 25 to 75, preferably 25 to 55 percent.
  • the bag filter dust may be be selected from the group comprising silicon smelter, ferrosilicon smelter, and low-carbon-ferrochrome (LCFC) bag filter dust. It may be the fresh dust newly collected from the bag filters, or it may be the lumps of dust formed after the fresh dust has been in contact with slurrying water and/or the dust exposed to cycles of wetting by rain and drying out. Optionally the lumps of dust may be crushed or otherwise ⁇ mminuted, for example to a particle size of minus 2 mm.
  • LCFC low-carbon-ferrochrome
  • the dust or lumpy material may be added to and mixed into the reaction medium in dry form Or it may be converted into a slurry with water prior to addition to the reaction medium.
  • this type of dust (as produced at the LCFC plant of Middclburg Ferrochrome, Middelburg, Mpumalanga province) has an appreciably lower silica content than the bag filter dusts from silicon and ferrosilicon furnaces, and contains several oxides of other metals, notably Fe, Cr, Al, Ca and Mg, in concentrations above 0,5% .
  • Table II below shows this material to be appreciably coarser than silicon smelter bag filter dust (about 71 % ⁇ 1 ,5 ⁇ m) and ferrosilicon smelter bag filter dust.
  • the LCFC dust is less reactive, and appreciably more undissolved material is left in suspension at the end of a production run than with alkali metal silicate solutions produced from the other two types of dust.
  • a higher temperature of about 60" is required to initiate the reaction, which is appreciably higher than for mixtures with the other types of dust.
  • more frothing occurs with reaction mixtures comprising the LCFC dust, and it is desirable to equip the reactor vessel with means, for example a water sprinkling rose, to keep frothing under control.
  • the alkali metal hydroxide may be added in the form of a solid, for example flakes, or in rhe form of a solution of convenient concentration, for example as 48 to 50 % alkali metal hydroxide solution (m/v), as is obtainable in the trade.
  • the order and method of addition of the alkali metal hydroxide and the dust are not critically important.
  • the alkali metal hydroxide and the dust may, for example, be added alternately as portions of the total complement of each.
  • the full charge of alkali metal hydroxide may be added to a suitable quantity of warm or ambient-temperature water in the reactor, and after heating the reaction mixture, if required, to at least 70 °C, the dust may be added in portions or continuously with agitation and further heating to maintain the temperature above 70°C until the reaction is substantially complete.
  • the alkali metal hydroxide solution and the dust may be continuously and simultaneously added to the reactor, initially charged with the requisite volume of hot water, while maintaining the temperature of the reacting mixture at or above 80°C.
  • Excessive temperature rises and/ or frothing may be controlled by the addition of water, for example water at ambient temperature. Frothing, it has been found, is readily controlled by water addition by means of a water rose.
  • the SiO 2 - alkali metal oxide ratio of the product solution may be effectively controlled.
  • Control of the total dissolved solids content of the product is achieved by controlling the quantity of water with which the reactor is initially charged, die amount added to the mixture in the course of the run, and the amount of dilution water, if any, added at the end of the run.
  • alkali metal silicate solution produced by the reaction between any one of the types of bag filter dust referred to above (i.e. silicon smelter, ferrosilicon smelter or LCFC bag filter dust) and the requisite amounts of hydroxide and water, have a significantly lower density and a substantially lower viscosity than the corresponding alkali metal silicate solution (i.e. of the same SiO 3 : alkali metal oxide ratio and total dissolved solids content) produced by the conventional melt process.
  • commercial 3,3: 1 SSS of total dissolved solids content 37,85% has a density of 1,395 kg/dm 3 and a viscosity of 200-400 C.P.
  • the corresponding SSS (with the undissolved solids suspended) produced by the dust/NaOH route has a density of from 1,35 to 1,36 kg/dm 3 when the dust is of the LCFC type, and from 1.28 to 1,33 kg/dm 3 at 20 ⁇ C when the dust has a ferrosilicon or silicon smelter origin; and at 20 °C these SSSs have viscosities which are substantially lower than that of die commercial product, with a "feel" to the hand not very different from that of water.
  • a total dissolved solids content of about 70% and 65% may be achieved when the bag filter dust is respectively of the silicon smelter/ferrosilicon smelter and of the LCFC type
  • a high-concentration SSS or KSS of the present invention offers important advantages. Because of the simplicity and relative cheapness of the process equipment required for the process of the present invention to those of a plant for SSS or KSS production using the melt process, a plant using the process of the invention may readily be set up and operated, and the product therefore delivered hot, on the same site as a plant having a relatively large demand for high-concentration SSS or KSS. Moreover, SSS or KSS, particularly of a high SiO 2 :alkali metal oxide ratio such as 3,3:1 SSS, may generally be produced according to the present invention at a cost significantly lower than that of the conventional melt process.
  • a typical example of the above is a plant for briquetting metal oxide ore fines, such as chromite or manganese ore fines, using SSS as the binding agent.
  • SSS a plant for briquetting metal oxide ore fines, such as chromite or manganese ore fines, using SSS as the binding agent.
  • Such plants require a SSS which is preferably of a higher concentration than can at present be readily supplied on site (e.g. at a typically remote mine or ferrometallurgical smelting works).
  • Bag filter dust was produced in the silicon furnaces of Silicon Smelters in Pietersburg, Northern province, and thereafter slurried with water into a slimes dam, after which the slimes dam contents were allowed to dry and the lumpy material transferred to a dump. Some of these air-dried lumps were collected and pulverised in a hammer mill fitted with an 800 micron screen. The pulverised material analysed approximately 91 % free SiO 2 , the remainder being largely moisture (about 6%), and free carbon.
  • a 2 litre tinplate can was used to produce 2 litre samples of SSS and KSS the compositions of which are given hereinafter, together with comparative data for SSS and KSS taken from the catalogue of Silicate & Chemical Industries (SCI), of Wadeville, Gautengzhou.
  • SCI Silicate & Chemical Industries
  • the can was charged with about 1,3 litres of hot water from a domestic geyser, and about half of the weighed out NaOH or KOH flakes (both assumed to be 98% pure) added to the water charge with stirring.
  • a KSS mass ratio of 1,45:1 is equivalent to a molar ratio of about 2,25:1 , and a mass ratio of 2,15: 1 to a molar ratio of about 3,3:1

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Silicon Compounds (AREA)

Abstract

L'invention concerne un procédé aqueux permettant de produire une solution de silicate de métal alcalin. Selon le procédé, on fait réagir une solution d'hydroxyde appropriée avec la poussière du filtre à manche issue du four d'une fonderie produisant du silicium, du four d'une fonderie produisant du ferrosilicium, ou d'une fonderie produisant du ferrochrome à faible teneur en carbone, et on maintient la température du milieu de réaction au-dessus de 70 °C, sensiblement jusqu'à la fin de la réaction, en appliquant une chaleur externe.
PCT/EP1997/002946 1996-05-28 1997-05-28 Procede pour produire une solution de silicate de metal alcalin WO1997045368A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU32557/97A AU3255797A (en) 1996-05-28 1997-05-28 Alkali metal silicate solution manufacturing process

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
ZA96/4301 1996-05-28
ZA9604301A ZA964301B (en) 1996-05-28 1996-05-28 Sodium silicate solution manufacturing process and product.
ZA972954 1997-04-08
ZA97/2954 1997-04-08

Publications (1)

Publication Number Publication Date
WO1997045368A1 true WO1997045368A1 (fr) 1997-12-04

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PCT/EP1997/002946 WO1997045368A1 (fr) 1996-05-28 1997-05-28 Procede pour produire une solution de silicate de metal alcalin

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AU (1) AU3255797A (fr)
WO (1) WO1997045368A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102674382A (zh) * 2012-06-05 2012-09-19 郑州大学 一种正硅酸锂材料的合成方法
WO2013017134A1 (fr) * 2011-08-02 2013-02-07 Bollerup Jensen A/S Composition de silicate métallique de faible viscosité

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2619604A1 (de) * 1975-05-06 1976-11-18 Skamol Skarrehage Molerverk As Verfahren zur herstellung von fluessigem wasserglas
FR2343698A1 (fr) * 1976-03-10 1977-10-07 Degussa Procede de traitement de poussieres fines volantes contenant de la silice pour l'obtention de precipites d'acides siliciques et de silicates
FR2370686A1 (fr) * 1976-11-11 1978-06-09 Degussa Procede pour la transformation de poussieres volantes de rebut, contenant du dioxyde de silicium, en un tamis moleculaire cristallin zeolithique de type y ayant la structure de faujasite
FR2370687A1 (fr) * 1976-11-11 1978-06-09 Degussa Procede pour la transformation de dechets en poussiere contenant du dioxyde de silicium en tamis moleculaire cristallin zeolithique du type a
EP0059088A1 (fr) * 1981-02-20 1982-09-01 THE WHITE SEA & BALTIC COMPANY LIMITED Solutions de silicates, leur préparation et leurs applications comme liants
ZA875531B (en) * 1986-07-28 1988-04-27 Phosphate Dev Corp Ltd Process for the manufacture of waterglass

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2619604A1 (de) * 1975-05-06 1976-11-18 Skamol Skarrehage Molerverk As Verfahren zur herstellung von fluessigem wasserglas
FR2343698A1 (fr) * 1976-03-10 1977-10-07 Degussa Procede de traitement de poussieres fines volantes contenant de la silice pour l'obtention de precipites d'acides siliciques et de silicates
FR2370686A1 (fr) * 1976-11-11 1978-06-09 Degussa Procede pour la transformation de poussieres volantes de rebut, contenant du dioxyde de silicium, en un tamis moleculaire cristallin zeolithique de type y ayant la structure de faujasite
FR2370687A1 (fr) * 1976-11-11 1978-06-09 Degussa Procede pour la transformation de dechets en poussiere contenant du dioxyde de silicium en tamis moleculaire cristallin zeolithique du type a
EP0059088A1 (fr) * 1981-02-20 1982-09-01 THE WHITE SEA & BALTIC COMPANY LIMITED Solutions de silicates, leur préparation et leurs applications comme liants
ZA875531B (en) * 1986-07-28 1988-04-27 Phosphate Dev Corp Ltd Process for the manufacture of waterglass

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 81, no. 18, 4 November 1974, Columbus, Ohio, US; abstract no. 108033z, page 148; XP002041793 *
CHEMICAL ABSTRACTS, vol. 82, no. 22, 2 June 1975, Columbus, Ohio, US; abstract no. 142233v, page 133; XP002041794 *
CHEMICAL ABSTRACTS, vol. 84, no. 16, 19 April 1976, Columbus, Ohio, US; abstract no. 107882a, page 135; XP002041795 *
CHEMICAL ABSTRACTS, vol. 84, no. 20, 17 May 1976, Columbus, Ohio, US; abstract no. 137974z, page 148; XP002041796 *
CHEMICAL ABSTRACTS, vol. 86, no. 4, 24 January 1977, Columbus, Ohio, US; abstract no. 19116q, page 152; XP002041797 *
CHEMICAL ABSTRACTS, vol. 88, no. 19, 8 May 1978, Columbus, Ohio, US; abstract no. 135612p, page 457; XP002041798 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013017134A1 (fr) * 2011-08-02 2013-02-07 Bollerup Jensen A/S Composition de silicate métallique de faible viscosité
CN102674382A (zh) * 2012-06-05 2012-09-19 郑州大学 一种正硅酸锂材料的合成方法
CN102674382B (zh) * 2012-06-05 2014-10-15 郑州大学 一种正硅酸锂材料的合成方法

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