DE1210112B - Process for making hydrated calcium silicate products - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C09c

German class: 22f-9.

Number: 1210112.

File number: J 22199IV a / 22 f

Filing date: August 2, 1962

Opening day: February 3, 1966

The invention relates to the manufacture of improved hydrated calcium silicate products. In particular, the invention is concerned with an improved method for buffering the fundamental, shafts of hydrated calcium silicates.

Hydrated calcium silicate particles are used as fillers, pigments, extenders, etc. for paints, Paper, rubber, plastic and similar products are known. For some purposes there are Silicates have been useful in varying degrees. Calcium silicate products are already known as Pigments or fillers to be used are treated with aluminum sulfate solutions. However own these calcium silicate compounds available today are typically one or more Properties such as relatively high solubility, high alkalinity or basic pH - inter alia that make them unsuitable and / or impractical for many uses or products, in which an essentially completely insoluble ao or "inert" and / or approximately neutral or even acidic filler or pigment which otherwise has properties that differ from those of the highly absorbent Calcium silicate does not distinguish, effectively and economically many filler, pigment or extension fabric requirements in the dye, paper, gum, plastic and the like Industries could meet.

The invention relates to a process for the preparation of hydrated calcium silicate particles and the product produced thereby and is characterized in that stable, hydrothermally formed, hydrated calcium silicates of the high temperature phase are hydrothermally treated with aluminum sulfate at a temperature of at least 177 ° C, preferably between 177 and 232 ⁰ C, in an amount and for a period of time sufficient to cause the reaction of at least 5 percent by weight, preferably 7.5 to 60 percent by weight, of the total CaO component of the hydrated calcium silicate with aluminum sulfate. Preferably, the hydrated calcium silicates are selected from the group comprising xonotlite and a synthetic hydrated calcium silicate having the composition

2 CaO • 3 SiO ₂ • 1-2.5 H ₂ O

and mixtures thereof. In particular, the product created in this way should have an »alum requirement« require no more than 4 ml of an aqueous solution of 0.0216 g aluminum sulfate per milliliter, to get a pH above 5.

Process for making hydrated
Calcium silicate products

Applicant:

Johns-Manville Corporation, New York, N.Y.

(V. St. A.)

Representative:

Dipl.-Ing. H. Seiler and Dipl.-Ing. J. Pfenning,

Patent attorneys, Berlin 19, Oldenburgallee 10

Named as inventor:

Carl Rene van der Linden,

Bound Brook, N.J .;

James Peter Leineweber, Sqmmerville, N.J.

(V. St. A.) '

F i g. Figure 1 shows the effectiveness of the treatment of the invention and the pH properties of the product this treatment in comparison with those methods which do not fall within the scope of the invention;

F i g. 2 shows the non-responsiveness of the hydrated Calcium silicate products with a low temperature phase, such as calcium silicate hydrate I, against all Types of treatment including the new method according to the invention;

F i g. 3 shows the relative effectiveness of the method according to the invention to various hydrated calcium calcium compounds of the high temperature phase; . . "..-

Figure 4 shows the long term alum resistance of Products treated according to the invention.

Typical hydrated calcium silicate products react when immersed in an aqueous, acidic medium In the course of a process or during the manufacture of a product - e.g. B. at the Finishing during papermaking, often adding alum (aluminum sulfate) to the Keep the pH of the equipment roughly in the range of 4 to 6 - with the acidic component (s) of the medium, resulting in an overall increase in pH. Therefore, as often as it is essential or at least it is desirable to maintain or restore the low pH of the medium, an additional amount of the acidic or acid generating component can be added to

609 503/356

3 4

the pH at the desired or origin- The extent to which the aluminum sulfates Maintain or restore level. treatment of hydrated calcium silicate on Such a procedure is often costly and prohibitions are put in place, of course, depends on the relative intrinsic oneself therefore for many manufacturing processes and trials or molar ratios of the calcium products. 5 aluminum sulfate added to the silicate compound

The invention leads to new hydrated and can of uneconomical stoehiometric calcium silicates, which show extremely small pH proportions, ie an essentially complete and other advantageous properties that they or total reaction or consumption of in particular as fillers, pigments, lengthening whole make available calcium oxide component of the agent, etc. suitable, namely in products io calcium silicate, consisting of 1 mol Al ₂ (SO ₄ I ₃ on or process, the media with relatively little or 3 mol CaO, down by any proportion or percentage acidic pH- The new compositions down to the lowest effective SiHcatprodukte according to the invention are produced limit of at least about 5% calcium oxide content by running stable hydrated calcium silicate on the special calcium silicate compound through the high temperature phase with aluminum. with aluminum sulf at treated miniumsulfat are treated or react, in calcium silicate products for many purposes temperatures of at least 177 ° C and preferred are those that result from a treatment with, in a range of 232 and 287 ° C, sufficient aluminum sulfate, thus about 7.5% A temperature of about 232 ^° C. is recommended for reasons of the available calcium oxide of the special silicate, effectiveness and economy, most to _{react to 20 [ie 0.025 mol of Al 2} (SO ₄ ) S per mol of CaO]. Furthermore, the treatment or the effectiveness of the aluminum reaction described should include sufficient aluminum sulphate and sulphate treatments as well as those of the known ones to be carried out to a point where little- process, ie the extent or the degree, up to at least 5 percent by weight of the calcium oxide compo- which the treatments reduce or have reacted the basic pH values of the component of the special silicate with the aluminum sulfate 25 treated calcium silicate product, provided that they suppress, can be measured by the amount of the aluminum theoretical stoehiometric proportions of the aluminum sulfate, that is needed to make a miniumsulfats and calcium oxide 1 mole aluminum sludge one with a given amount of aluminum minium sulfate to 3 moles calcium oxide. Bring the sulfate treated calcium silicate to a pre-level to which it is desirable or appropriate to bring the correct pH, or to pre-treat the aluminum sulfate treatment above the maximum pH specified above for a sludge minimum of 5% Adding or stretching an aqueous medium after the addition of an aluminum sulfate-treated calcium silicate requirement depends on the end product. right. The effectiveness or extent

As already mentioned, the high temperature treatment in which the treatment reduces the basic pH values of the calcium silicate only treated with aluminum sulphate according to the invention, if it presses on the high temperature phase and at the same time using suitable means for measuring hydrated calcium silicate compounds are subsequently referred to as "alum requirement", namely, for example, hydrothermal rees treated with aluminum sulfate or buffered action products of an aqueous suspension of calcium silicate lime. The special test used to determine the "alum requirement" of the treated rial, such as diatomaceous earth, quartz, etc., at temperatures of calcium silicate in the following examples and of at least 188 ° C and preferably about 232 ° C for and a reacting silica-containing material. Whole description is used, unless examples of suitable calcium silicate compounds of the other are given, so that 0.5 g of the high temperature phase is the calcium silicate xonotlite 45 sample of the special aluminum sulfate treated (5CaO.5SiO ₂ -H ₂ O ) and a calcium silicate compound, calcium silicate, slurried in 400 ml of water, dung with very low solubility, which gradually adds the formula to 1 ml of aluminum sulfate solution.

2CaO 3 SiO 1 2 5HO, the 0.0216 g of hydrated aluminum

^{Contains 2} ' ² sulfate [Al ₂ (SO ₄ ) S' 18H ₂ O] per milliliter, and

and a remarkable x-ray deflection 50 the pH is measured after stirring for 5 minutes with very strong lines d - 3.12 Å and d = 4.12 Å. The "alum requirement" is expressed and has a center line at d = 8.34 Å. The pre- as milliliters of the aluminum sulfate solution, the compounds mentioned must be added with a high temperature phase in order to bring the pH of the Aufkönnen from slurry to 5.0 through the hydrothermal reaction.
Lime and a source of reactive silicon- 55 The aluminum sulfate treatment of the stable dioxyds in the corresponding molar ratios of hydrothermally produced hydrated calcium-1 mol CaO per mol SiO ₂ and 0.5 to 0.7 mol CaO süicatverbindungen of the high temperature phase can per mol SiO ₂ in aqueous suspension at temperatures substantially in any conventional or suitable manner ren of at least about 188 ⁰ C, are carried out preferably 323 ⁰ C, whereby it is only important be produced for times of about 2 hours. 60 that the hydrated calcium silicate of the high temperature can be produced by changing the molar ratios of the reactive temperature phase and the aluminum sulfate in a lime and the silicon dioxide-containing compound at temperatures of at least 177 ° C and preferably at 232 ° C ° C together, the mixtures of the different are brought together. Furthermore, the aluminum gene hydrated calcium silicates of the high temperature sulfate treatment can be practically and economically contained in the temperature phase, and such mixtures are carried out in the same reaction kettle or vessel in the same manner in the practice of the invention, which is used for the synthesis of the reversible. High temperature calcium silicate perform by

5 '6

simply add an aqueous solution of aluminum sulfate 200 g / l to the reaction vessel until the

is added directly to the reaction vessel after aluminum sulfate content 2.4 kg per kilogram of CaO

the hydrothermal formation of the hydrated CaI component of calcium silicate (about 0.20 mole des

ciumsilicate product essentially completely hydrated aluminum sulfate per mole of CaO)

and the synthesis temperatures are maintained. Such 5 held, and the combined reaction mixture was

a process, namely the addition of the aluminum at a temperature of about 238 ⁰ C for an additional

sulfate held directly to the contents of the hot reaction borrowed time of about 30 minutes. The content

kesseis, brings considerable savings in consumption. The reaction vessel was then filtered, dried

equal to a subsequent heating of all grain and ground,

components to the appropriate reaction temperature. ίο ρ · ι *

The aluminum sulfate reagent that was used for the exemplary embodiment 3
tion of the invention is suitable, ordinary A high pressure reaction vessel was initially alum for papermaking or any of the commercial types of aluminum sulphate, which were heated to a temperature of about 232 ° C and heated to the market after draining the condensate are include. 15 38.6 diatomaceous earth suspended in 2731 water, filled,

The mechanism of the invention is somewhat problematic, whereupon the temperature is brought back to 232 ° C automatically; hence the following became theoretical. 45.4 kg of hydrated lime, also in 2731 explanations for illustrative purposes only and suspended in water, was then given to the reaction vessel not in the sense of limitation. However, observations, which have been added to the circumference and the temperature again ranged to 232 ° C., show that the handling was brought and kept there for 2 hours during a reaction time of the stable hydrated calcium silicates. The proportions of lime and that of the high temperature phase with aluminum sulphate in the case of material containing silicon dioxide were _{calculated to give the required temperatures to CaO: SiO 2} molar ratio of 1.0. After a reaction product of the aluminum sulfate had completed the reaction time, the reaction would result in calcium silicate, in which a protective coating is formed, drained into a storage container, or a conversion of the surfaces and all solids in the sludge occurs through the hydrated calcium silicate particles, which evaporate a known volume The mud provides effective resistance to further acidity to dryness determined to provide the proportion of attack. hydrated calcium silicate for the following

The following examples explain the 30 action to be taken to determine. Then there was enough aluminum invention including various variations, with about 15% of the CaO content in their execution. of the calcium silicate to react (0.237 kg of the hydrated Aluminum sulphate per kg of hydrated

Example 1 sized calcium silicate) dissolved in about 911 water

35 and the aqueous suspension of the hydrated

38.7 kg of diatomaceous earth suspended in 2731 water, calcium silicate in the storage container below was fed to a reaction kettle, which was added by continuous stirring, with the steam preheated to a temperature of 232 ° C, contents over 1 hour at a temperature of about and about Condensate was withdrawn. After the 71 ⁰ C was kept. This addition of the aluminum temperature of the reaction ^{vessel back to 232 0} C resulted in a considerable reversal, 45.4 kg of hydrated lime were thickened in the sludge, and it was necessary to add 2731 water (which is a calculated CaO: SiO ₂ -MoI- add additional water, about half the ratio of about 1.0 results) and the original sludge volume to bring the sludge temperature again to 232 ° C and to keep this in a workable state. The value held for about 1.5 hours. Finally, 45 treated product was filtered in a rotary, 8.4 kg papermaking alum in 183 l water vacuum filter, dried (0.024 moles hydrated aluminum sulfate per mole dried in an oven at 116 ° C and ground.

CaO) was added to the reaction vessel and held there for about The "alum requirement" of the products of Examples 1 ³ Z ₂ hours, so that a total Re and 2, the one with 7.5% ^{un (} i one with 60% aluminum action time of 50 xonotlite sulfate treated according to the invention umvon 232 ⁰ C to give about 2 hours at a temperature. the product was then put into one of example 3, a discharged at 7.5% in a conventional storage tank and treated with a rotatable manner xonotlite and an unbreakable vacuum filter filtered, dried in the oven and traded xonotlite as a comparison sample was pulverized according to the process steps described above. 55 carried out, ie 1 ml of additions of B e 1 s ρ 1 e I 2 aluminum sulfate solution with 0 0216 g of hydrated

An aluminum sulfate treated xonotlite aluminum sulfate [Al ₂ (SOJ ₃ · _{18H 2} O] per milliliter in calcium silicate was prepared by adding an aqueous 0.5 g sample of each of the special aluminum reaction mixture of 81801 diatomaceous earth sulfate treated calcium silicate -Products and the xonotlite untreated with 63 g diatomite per liter and about 30901 lime- 60, slurried in 4000 ml water with 146 g CaO per liter in a reaction slurry, titrated and the pH value after a re-vessel for 1.5 hours stirring at a temperature of 238 ° C. for 5 minutes. The results were held. The relative proportions of lime and these tests were calculated in a graph for the components containing silicon dioxide, based on the "alum requirement" of the untreated calcium, so that a CaO: SiO ₂ molar ratio of 65 silicate oxonotlits and which according to previous practice results in 1.0. After completion of the reaction, the substances treated for 1.5 hours appeared agen. These results took to at a temperature of about 238 ⁰ C, shows the graph of FIG. 1. The "Alaunbedarf" An aqueous solution of aluminum sulfate expressed as milliliters of aluminum sulfate

solution that needs to be added to the about V ₂ hours at a temperature of about 232 ° C

Reduce the pH of the sludge to 5.0. was held together with enough

. . Aluminum sulfate reagent that about 7.5, 30, 40,

B e ι s ρ ι ei 4 _{50> 60? 90 0} ^ of _the CaO content could react. Of the

Three identical samples of a hydrated calcium 5 long-term "alum requirement" for each of the thus produced, ·

silicate compound of the low temperature phase, such as calcium sulfate treated with aluminum sulfate

it was identified in the literature as the phase calcium silicate for comparison and evaluation.

hydrate I (Taylor, Journal of the Chemical Society, made by adding '0.5 g of each of the samples in 400 ml

USA., P. 163, 1953), water was slurried, aluminum sulfate was added

by adding hydrated lime and a silicon- io to each slurried sample in an amount equiva-

Dioxide-containing material with a molar ratio of 1 to 0.086 legs per kilogram of calcium silicate,

0.6CaO: ISiO _{2 was added} at a temperature of 177 to the pH of each slurried

182 ° C measured and recorded against the sample as a function of time over a period of about 2 hours.

Response. Sample 1 was drawn as was. The results of these experiments, which are presented in

Comparative sample left untreated. The second 15 F i g. 4 show the remaining low

Sample was treated with sufficient aluminum sulfate pH value of 60% treatment. Because of the big

delt that 7.5%. the proportion of lime in the case of environmental differences in the stability of these samples is the

temperatures reacted. The third sample was plotted in time on a logarithmic scale, retained in the reaction vessel and with sufficient

Aluminum sulphate treated to 7.5% of the lime at 20 jj _e ispiel 7
Temperatures in the range of 177 to 182 ° C reacted. The "alum requirement" of each sample, which was determined exactly as in the case of ■ A hydrated calcium silicate of the high temden previous methods, perattirphase with low solubility, which the formula was recorded for comparison and represents the

Fi g. 2 of the. This experiment shows 25 2CaO-3SiO ₂ -I-2.5H ₂ O

accordingly shows that only the calcium silicates

the, higher temperature phase (above about 188 ° C, was with 10 kg of papermaking alum

preferably at about 232 ° C.) against acid levels [Al ₂ (SO ₄ ) S · 18H ₂ O] per 45.4 kg of the lime component

flow through treatment with aluminum sulfate in the hydrothermal reaction vessel during

can be done constantly. - 30 of a period of 30 minutes at one temperature

treated at about 232 ° C. This is enough AIu-

Example 15 miniumsulfat, around 7.5% of the CaO content

of the calcium silicate to react. A comparison of the

It has been a number of hydrothermal syntheses- Filtration rate of the above, with alum

Sen hydrated calcium silicate products of high 35 treated hydrated calcium silicate was made with

Temperature phase carried out, with lime and an identical, untreated hydrated CaI-

silicon dioxide-containing reactants with CaO: SiO ₂ - ciumsilicate compound of the high temperature phase

Molar ratios that range from 0.5 to 1.0 CaO and with low solubility. Under identi-

1 SiO ₂ increased, at temperatures of about 232 ° C see conditions was the filtration rate

of the aluminum sulfate treated product together for a period of about 1.5 hours

reacted. Each of the 85 kg / m ² · h, while the untreated product one

giving hydrated calcium silicate products, which gave a filtration rate of 39 kg / m ² · h,
in each case xonotlite, the slightly soluble calcium silicate
with the formula examples

2CaO-3SiO ₂ -1-2.5H ₂ O, ⁴⁵ _ΛΓ

Various pressure reaction vessels with an in-

referred to so far, or contents of 22.71 each with 438 g of diatomaceous earth, 'mixing these compounds was filled with 151 g of hydrated lime and 15.91 of water, the addition of enough aluminum sulfate to add a CaO : SiO ₂ molar ratio of 1.0 to give reaction vessel treated that 7.5% of the calcium oxide 50 and after the completion of a reaction time of 90 minutes part of the particular compound reacted, and that at 232 ° C, as the stable hydrated calcium -Reactions were produced for a period of about silicatxonotlit the high temperature phase V was continued for ₂ hours at temperatures of about 232 ° C-, aluminum sulfate was placed in each reaction vessel. The decreasing CaO: SiO ₂ molar ratio- added in 2.271 water, and after adding the hydrated calcium silicate only led to a reaction time of 55 y ₂ hours at 232 ° C, which resulted in a slight increase in the "alum requirement". The product drained from each reaction vessel, "alum requirement" of each of these products, as it is filtered in this, dried and ground. The aluminum test found is in the graph the sulfate treatments were shown at theoretical values in FIG. of 3, 6 and 30% of the amount of τ required,. . , Carried out 60 AluminiumsuHats to react with the CaO-P ^e proportion of calcium silicate (100%

Six identical samples of calcium silicate xonotlite aluminum sulfate treatment requires 1 mole of Alu-

the high temperature phase were according to the miniumsurfat on 3 moles of calcium oxide of the calcium

hydrothermal processes and the aluminum silicate product). If about 6% or greater

sulfate treatment of Example 2 prepared. The total amount of aluminum sulfate used was found

speaking xonotlite samples with aluminum - a final "alum requirement" of the product of

sulfate treated to a variable extent, each adding less than 0.14 kg of aluminum sulfate per kilogram

in an aqueous medium for a period of calcium silicate, while in the treatment with 3%

Aluminum sulfate the "alum requirement" was much higher .

Claims (2)

Patent claims: 1. A process for the production of hydrated calcium silicate products, in particular for use as pigments or fillers, by treating calcium silicates with aluminum sulfate, characterized in that stable, hydrothermally formed, hydrated calcium silicates of the high temperature phase are hydrothermally treated with aluminum sulfate at a temperature of at least 177 ° C, preferably between 177 and 232 ⁰ C, in such an amount and during such a period of time to reduce action are brought that at least 5 percent by weight, preferably 7.5 to 60 percent by weight, of the total CaO component of the hydrated calcium iMcat with aluminum sulfate implemented. 2. The method according to claim 1, characterized in that the hydrated calcium silicates Xonotlite, a synthetic hydrated calcium silicate with the composition 2CaO-3SiO ₂ -1-2.5H ₂ O
or mixtures thereof can be used. Considered publications:
German patent specifications No. 937 414, 964 714. 1 sheet of drawings 609 503/356 1.66 © Bundesdruckerei Berlin