AU700105B2

AU700105B2 - A processing method for white carbon

Info

Publication number: AU700105B2
Application number: AU81613/94A
Authority: AU
Inventors: Ju Chen Liang
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-20
Filing date: 1994-12-20
Publication date: 1998-12-24
Anticipated expiration: 2014-12-20
Also published as: AU8161394A

Description

_'II I P rres 1

AUSTRALIA

Patents Act 1990 Name of Applicant JU CHEN LIANG S" Actual Inventor(s) JU CHEN LIANG Address for Service GRANT ADAMS COMPANY, Patent Trade Mark Attorneys Level Santos House 215 Adelaide Street BRISBANE QLD 4000

AUSTRALIA

Invention Title A PROCESSING METHOD FOR WHITE

"CARBON

Details of Associated Provisional Applications Numbers The following statement is a full description of the invention including the best method of performing it known to me.

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rr~ A PROCESSING METHOD FOR WHITE CARBON Field of the Invention This invention relates to a processing method for white carbon which is the trade designation of a silica pigment which is a kind of coarse and nonpure silicon dioxide containing over 93% of Si0 2 Background of the Invention At present, the acid-base contact method is adopted for processing white carbon (with a content of silicon dioxide of over In this method water is added into sodium silicate to make it into liquid; then a certain amount of acid (such as sulphuric or hydrochloric acid) is added, and the liquid is stirred as much as possible until the liquid becomes milky (generally white in colour). After separation, a pasty substance milky white in colour is obtained.

o After being dried, smashed and ground, the white pasty substance becomes white and powdery, which is called white carbon. This white carbon can be tused as a stiffening agent. The silicon dioxide obtained by this method is still acidic (with a pH value of 5.5 to and contains 93-95% (in terms of weight) of 5i0 2 0a d 6% of water (in terms of weight), less than 0.1% (in weight) of chloride and less than 0.1% (in weight) of 25 magnesium oxide and calcium oxide.

.9 .r The above-mentioned acid-base contact method serves to neutralize the diluted liquid of sodium silicate by acid, such as sulphuric acid. This method has the following disadvantages. It is harmful to people and livestock since sodium silicate consists of about 50.69% of sodium oxide (Na 2 0) and 49.31% of I 31PI 1 I r- ul-s,~~ a a *Y a a oa aO .a a* a is a.r a a a

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silicon dioxide, and said sodium oxide will produce much heat during its mixing with acid and alkali and disperse foul poisonous and acidic sulphur dioxide fumes. The sulphuric acid used in this method is a strong acid, which is dangerous to the people engaged in handling and operation. And the acid-alkali mixed liquid (after neutralization) causes pollution to the surroundings when it is discharged. At a time when great importance is attached to protection of the environment, this method has to be improved.

Silicon dioxide is a good stiffening agent which can be broadly used. However, since the silicon dioxide processed by the above-mentioned method is an acidic silicon dioxide (normally called white carbon), it may have anti-affinity. Products (such as tyres and paper) made by using this kind of acidic silicon dioxide may have defects such as scaling and fragileness after being used for a certain period of time.

20 There are several other methods and processes in addition to the above-mentioned acidbased contact processing method, but these are not widely used because of the higher cost.

Summary of the Invention 25 The purpose of this invention is to provide a processing method, especially an economic method which can produce alkalescent white carbon (containing over 93% of Si02)in large quantity and which can improve the quality of downstream products made therefrom.

According to the invention there is provided se re 2a a method for preparing white carbon (silica pigment) Wcomprising the following steps: i) mixing and stirring sodium silicate and sea water at normal temperature and normal pressure in the absence of acid with the weight proportion of sea water to silica being at least 50:1; ii) allowing a white substance to be formed; iii) further processing said white substance to obtain the powdery white carbon product.

Thus the objective of this invention is achieved by the following steps; sodium silicate is :al, 15 mixed with sea water at normal temperature and normal 4: pressure and the mixture is stirred; the resulting white substance is separated; and it is processed into tee.

powdery white carbon. The mixing proportions of e sodium silicate and sea water in terms of weight are ideally 1:50 to 1:100 with the optimum proportion Sbeing 1:60. Sodium silicate can be dissolved in fresh water before being mixed with sea water. The a separated white substance can be washed with fresh So water before being processed into the powdery white carbon product.

The remarkable advantages of this invention are i I 1 L- Is I I- IY that a great quantity of white carbon can be produced by a simple technology and at a low cost as a result of using sea water; the discharged material will not cause any pollution to the surroundings; and the quality of downstream products can be improved since the white carbon produced by this method is not acidic.

Detailed Description of the Invention This invention is described in detail by the following detailed description and by the attached drawing.

Figure 1 is a flow chart showing the processing method for white carbon described by this invention.

According to the method of the invention, sodium silicate (Na 2 Sio 3 is mixed with sea water with stirring at normal temperature and normal pressure and then the resulting silicon dioxide is separated out.

Preferably the sea water to be used is clean sea water r. containing the following (in percentages by weight) about 0.2714 weight sulphate, about 1.9353 weight chloride, 1.0760 weight sodium, 0.1294 weight magnesium, 0.0387 weight calcium, about 0.0142 weight potassium, about 0.0087 weight bromine, about 0.0008 weight strontium, •about 0.0004 weight boron and about 0.0001 weight fluoride.

Sodium silicate (Na 2 Si 3 can be resolved into S"sodium oxide (Na 2 0) and silicon dioxide (Sio 2 The preferred processing method for white *u carbon described in this invention is shown in Figure 1.

At first, fresh water 2 is added into the sodium silicate raw material 1 with stirring so as to create liquid sodium silicate 3 with adequate flowability for further processing. Then sea water 4 is added into the above mentioned liquid 3 at about 50 to 100 times (the optimum is 60 times) the weight of the sodium silicate; with as much stirring as possible. At this moment, the sodium oxide in the sodium silicate dissolves in the sea water 4 while the silicon dioxide which does not dissolve in sea water is segregated. In other words, the liquid is kept j still after having been stirred which creates a separable white substance 5 and sea water containing sodium oxide 6. This white substance 5 is silicon dioxide and a small amount of residual sodium oxide.

Fresh water 7 is then added into the abovementioned white substance 5 with stirring so as to wash it. since sodium oxide dissolves in water while silicon dioxide does not, the remaining sodium oxide can be eliminated by this addition of fresh water. As a result, pure white substance 8 can be separated out leaving water solution 9. White substance 8 is further processed into white carbon 13 containing silicon dioxide of very high purity while the water solution 9 will contain residual dissolved sodium oxide and other substances. This white carbon forms a pure and clean white substance containing silicon dioxide of very high purity. Tests show that the *09* pH value of this substance is slightly alkalescent. By using conventional methods of dewatering, drying, smashing and grinding to further process the abovementioned pure and clean white substance 8, the white carbon product 10 can be obtained. Nevertheless, this too 0pure and clean white substance 8 can alclo be processed to get powder-like white carbon product 10 by using other conventional methods.

Since the sea water containing sodium oxide 6 comprises sea water, fresh water and a certain amount of j~i sodium oxide, the sodium oxide can be easily captured by 630' the experienced chemist for further processing.

Hereunder, a method is recommended: Dodecyl benzenesulfonic azid 11 may also be added to the above-mentioned sea water containing sodium oxide 6 and stirred, and the dodecyl benzenesulfonic and sodium oxide will. combine to produce sodium dodecylbe~nsene sulfonate 12. In this way, the side product, aodiumn dodecylbenzene sulfonate 12, may b1 sl--I-- 04 44 8 a 00r a a 0400 *o 4 o e 44 0 °4 0 0;f444 4404 0 *r 4,44* -4 ,r produced so as to cut down the cost of the processing method of this invention. This sodium dodecylbenzene sulfonate can be used in detergent refining. The end liquid 13 which is separated from the dodecylbenzene sulfonate 12 is similar to sea water but can not be recycled and reused. However, the end liquid 13 which is separated in this way is clean and non-poisonous.

It has been discovered, through repeated tests, that the silicon dioxide inside the sodium silicate can be fully separated only if one portion of sodium silicate is mixed by stirring with over sixty portions of sea water. If the sea water is only 40 to 50 times that of the sodium silicate, there will be some, although incomplete, separation of silicon dioxide. The presence of the milky white colour indicates the separation of silicon dioxide. However, the weight of the wet and white silicon dioxide after dewatering will decrease progressively with the reduction of the amount of the sea water, as shown in Table 1. If clean sea water is added into the waste liquid in the separating machine with stirring, then there will still be the reaction in which milky silicon dioxide floats to the top of the waste liquid (after leaving to become stationary) and white silicon dioxide can still be separated with decreased amount. If one portion of sodium silicate is added with two portions of sea water and stirred, there will be no reaction at all, i.e. there will be no production of milky white reactant, and no white substance will remain on the filter paper after dewatering. That means the critical point from which the silicon dioxide can be fully separated from sodium silicate is to add sea water which is 60 times that of sodium silicate.

Examples 80 or 100 portions of sea water were added into one portion of sodium silicate before mixing, leaving to stand and dewatering. White and wet silicon lp~ ql ~C1~ q dioxide was produced, the weight of which was very close to the weight of silicon dioxide (49.31% in weight) contained in sodium silicate. Therefore the weight proportion of the mixture between sodium silicate and sea water should be 1:50 to 1:100 with the optimum one of 1:60. In other words, when one portion of sodium silicate is mixed with 60 portions of sea water (in terms of weight), almost 100% of the silicon dioxide contained in sodium silicate can be separated.

Table 1 Reaction Results of One Portion of Sodium Silicate Mixed with *r 9 9,.

9 9o 9 99 9 49 *9 9 4a 9~ Different Portions of Sea Water (in Terms of Weight) Portions of Sea Water 5 10 20 30 40 50 60 80 100 200 of wet SiOC to be separated 0.13 0.48 0.98 1.80 2.25 2.64 2.910 2.910 2.910 2.910 of dry SiCk to be separated 0.03 0.08 0.18 0.30 0.380 0.440 0.485 0.485 0.485 0.485 ro -a I~ C I~ i7 As mentioned above, the procedure is to dilute the raw material of sodj Am silicate first, then to mix it with sea water and stj- to produce the white substance, which can be processed into white carbon. When the white carbon is used for some products which do not have strict requirements on pH value, no washing is necessary.

In summary, this invention takes sodium silicate as the raw material, mixes it with an adequate amount of sea water, then an alkalescent white carbon can be finally separated. Furthermore, the water containing sodium oxide 6 contains a certain amount of sodium oxide which can be easily captured by the experienced chemist to produce a valuable byproduct. If the sea water containing the dissolved sodium oxide is added with dodecyl benzenesulfonic acid with stirring, then the I dodecyl benzenesulfonic acid will be combined with the sodium oxide to create sodium dodecylbenzene sulfonate.

Thus the side product, sodium dodecylbenzene sulfonate, S can be easily obtained.

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Claims

1. A method for preparing white carbon (silica pigment) comprising the following steps: i) mixing and stirring sodium silicate and sea water at normal temperature and normal pressure in the absence of acid with the weight proportion of sea water to silica being at least 50:1; ii) allowing a white substance to be formed; iii) further processing said white substance to obtain the powdery white carbon product. 0 0

2. A method of claim 1 wherein said sodium silicate is first dissolved in fresh water before said mixing and stirring of said sodium silicate and sea water.

3. A method of any preceding claim wherein the white substance created as a result of the reaction of sodium silicate and sea water is washed with fresh water before it is further processed into said powdery white carbon product. 0 0

4. A method of any preceding claim wherein said white carbon is alkalescent white carbon containing over 93% SiO 2 A method of any preceding claim wherein the I~b- I Al,~ 9 mixing proportions of said sodium silicate and said sea water by weight are 1:50 to 1:100.

6. A method of claim 5 wherein said mixing proportions are 1:60 to 1:100.

7. A method susbtantially as described herein with reference to the Examples.

8. White carbon (silica pigment) obtained by the method of any preceding claim. DATED this Third day of November 1998. ii Ic I *4 4 #4 4 4 .4 o .q 4 4r 441 JU CHEN LIAN By his Patent Attorneys FISHER ADAMS KELLY for a contai l an ade silica and no silica wi) b -an be white advant carbon will n the wh o which a 0 o4 0 0 p r p *lW R 1Q ABSTRACT This invention relates to a processing method kind of white carbon (non-pure silicon dioxide ning SiO 2 of over According to this method, quate amount of sea water is added into sodium te and stirred sufficiently at normal temperature rmal pressure. This will convert the sodium te into silicon dioxide, while the sodium oxide e dissolved in the sea water. The silicon dioxide separated before being processed to a powdery carbon product, This invention has the following ages. It can produce a great quantity of white in an economic way. Its discharged waste liquid ot cause any pollution to the surroundings. And ite carbon produced by this method is alkalescent, can improve the quality of its downstream products.