JPS61146340A - Storable and pumpable aqueous slurry and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to aqueous slurries, particularly non-settling, flowable aqueous slurries of sodium dithionite that remain in pumpable form without significant swelling, settling or gelling.

Conventional technology Sodium dithionite (usually sodium bisulfite,
(less accurately called sodium hydrosulfite) is a strong reducing agent that has been used for some time for bleaching, especially textiles and groundwood pulp semi-chemicals, wood pulps such as pulp. .

Sodium dithionite was usually produced by different patented processes featuring zinc dust, sodium formate, sodium borohydride or sodium bisulfite (electrolytic). Such methods are described, for example, in U.S. Pat. No. 29387
No. 71; No. 3004825; No. 3259457; No. 3411875; No. 3718732; No. 38722
No. 21; No. 3887695; No. 3897544; No. 3927190; and No. 4127642.

The products of these methods are referred to herein as zinc-
induction, formate-induction, borohydride-induction and electrolysis-
Suppose that the derivative is sodium dithionite. Since zinc dithionite produced by the zinc process is no longer ecologically acceptable, zinc dithionite is converted to sodium dithionite by adding sodium hydroxide or carbonate, thereby converting it into sodium dithionite. Zinc carbonate is precipitated and removed by filtration.

When anhydrous sodium dithionite crystals are dissolved under aerobic or anaerobic conditions to produce large quantities of aqueous solutions, the resulting solutions cannot be stored for long-term use. Since the sodium dithionite solution hydrolyzes in neutral conditions, decomposition proceeds rapidly from that point by self-chain reaction as the decomposition products create acidic conditions which accelerate decomposition.

However, aqueous solutions of dithionite salts are commercially acceptable in US Pat.
When stabilized by additives such as those described in the patent, they decompose at industrially acceptable rates. These additives include chelating agents, sodium carbonate, sodium tripolyphosphate, sodium hydroxide and amines.

Although such stabilized solutions can protect the anhydrous dithionite crystals from decomposition for long enough periods for shipping and routine industrial use under suitable conditions,
Storage under dry inert gas in a sealed container was the more common practice. Even though the crystals are thereby chemically stable for long periods of time, they begin to decompose as soon as they are exposed to air and moisture when the container is opened for use.

Furthermore, solutions of sodium dithionite available on the market have a concentration of 12-13% when combined with suitable additives and, moreover, generally require refrigeration during shipping and storage, making them difficult to transport. It's expensive. Thus, transporting about seven times as much water as product tends to make the sale of goods distance dependent. As a result, the slurry eliminates the storage costs and difficulties associated with sodium dithionite in solution form, without reducing the convenience that the purchaser derives from solution.
seemed to offer an interesting means of avoiding or at least minimizing.

However, the economical production, stabilization, handling, and shipping of such slurries is not straightforward. It is also not easy to produce suitable suspensions without stirring, so that they can be pumped from tank cars after transport there by ship.

Indeed, the complexity of the idea is readily appreciated when one considers the variety of methods available for producing sodium dithionite, including unique by-products, crystal structures, etc. Additionally, slurries have not been extensively studied or commercially utilized like other forms of sodium dithionite.

U.S. Pat. No. 3,536,445 describes a method for producing sodium dithionite from a sodium-zinc alloy by first making zinc dithionite and then converting it to sodium dithionite by adding sodium hydroxide. It is listed. After removing the zinc hydroxide by filtration, the dihydrate of sodium dithionite is salted out from the mother liquor using sodium chloride and alcohol to form a slurry.

U.S. Patent No. 3,804,944 discloses the
8% (relative to dithionite) 30 tislary (formate-derived sodium dithionite 18.5%)
and zinc-derived sodium dithionite11. ．． !
1) shows some stability storage data. Tests have shown that these slurries require frequent agitation to prevent condensation and processing difficulties.

U.S. Pat. No. 3,839,217 discloses a method for reducing the particle size of sodium dithionite crystals and/or adding a suspending agent or thickener to a liquid containing the crystals, such as an alcoholic salt solution. We show that it is possible to create flowable, homogeneous, pourable dispersions of solid dithionite particles that are chemically and physically stable for long periods of time by introducing dithionite There shall be substances such as salts in brine and/or alcohol that inhibit the dissolution of . The majority of the particles are hexiteal about 0.6-0.8 microns in size. Methyl cellulose, hydroxyethyl cellulose,
Holivinyl alcohol, guar gum and other conventional thickening, dispersing or suspending agents can be used. The thickened dispersion typically has a Brookfield viscosity of 9000 c, ps- and contains up to 34 g of Na2S204.

U.S. Pat. No. 383G1218 maintains a crystalline zinc dithionite or alkali metal dispersion by continuous or periodic mechanical stirring so that the crystals can be stored for long periods of time without decomposition. To achieve this, a method is provided in which the dispersion medium is aqueous or non-aqueous and contains a substance that inhibits dissolution of dithionite solids.

The liquid volume must be at least 6.5, the viscosity of the dispersion must be below about 50,000 centipoise, and the inhibitor may be a water-soluble organic compound or a saturated salt solution or a mixture thereof. Thickening and suspending agents may be used. Suitable thickening and suspending agents include polysaccharides, water-soluble polymers, and moderate molecular weight proteins. Representative agents include guar gum, tragacanth, gelatin and starch.

U.S. Pat. No. 4,283,303 discloses that a sodium dithionite solution is heated to 220 to 250 degrees Fahrenheit to produce a substantially stable slurry containing 30 to 35 percent by weight of sodium dithionite. (about 104.4° C. to about 121.1° C.), and the solutions and slurries are placed under a vacuum of at least 25 inches (635 mm) Hll.
A method is described in which the slurry is maintained at a temperature below 155° C. (about 43.3° C. to about 68.3° C.) for evaporation, and the resulting slurry is rapidly cooled while stirring. The vacuum is preferably between 26.5 and 27.5
inch (673.1 to 698.5 mW).

A preferred sodium dithionite solution is a zinc-induced dilation solution to which is added 4-5% by weight of sodium dithionite, NaOH and a chelating agent as a stabilizer.

Although these evaporated slurries have very good stability, they have experienced settling problems over a period of 2 to 5 days, especially under the vibrations created by tank truck transport. Such settling and subsequent hardening resulted in a cargo that could not be unloaded by pumping as is customary.

Slurries are commonly used as foods, coatings, paints, dyes, explosives, oil well fluids, etc., and often contain natural or synthetic rubbers.
A liquid colloid system is formed in which solid particles are dispersed. Such rubber-containing liquid systems, without solid particles, are considered to be sols, and more precisely, when based on water, are called hydrosols.

Rubbers typically provide viscosity to the sols in which they are formulated, thereby providing a thickening agent function. When a shear force is generated by stirring the sol and no change in viscosity occurs, the behavior of the thickener is said to be Newtonian flow. When the viscosity of the sol at rest is greater than when a shear force is applied by stirring, when the viscosity decreases when the applied shear force increases, and when the viscosity decreases when the magnitude of the shear force decreases. If it recovers quickly, the behavior of the thickener is said to be plastic. A sol is described as pseudoplastic if the flow rate increases more rapidly than is normal with respect to the applied shear stress. Generally, when the sol is stationary, the molecules of the plastic thickener arrange themselves in a more or less stable manner. Application of shear forces is necessary to disrupt this stable molecular arrangement and generate a sol. The shear force required to generate and flow the sol is called the yield point or gel strength. Once the gel strength of the plastic sol is overcome, the viscosity of the sol decreases proportionally when large shear forces are applied.

A large number of natural and synthetic rubbers are widely used for the production of hydrosols. An advantageous gum for many hydrosols is the Gu/- tree (Cyamopsi
It is a galactomannan gum, such as guar gum, derived from the endosperm of P. stetragonolobus.

Another water-soluble gum that is increasingly used is Xanthomonas hydrophilic colloid (commonly called xanthan gum), which is due to the action of various species of the genus Xanthomonas on carbohydrates (and such materials). can be manufactured. Carbohydrate Bacterium Xanthomonas Campegtris
; the fermentation product of the reaction of a preferred bacterial strain is produced by Kelco Corporation.
) (manufactured by San Diego, Calif.), available commercially as "Kelzan" (manufactured by San Diego, Calif.). Dilute the fermentation liquor with water to reduce its viscosity and optionally centrifuge or filter the diluted fermentation liquor to remove suspended insoluble solids.Salts such as potassium chloride and methanol or inpropyl alcohol A non-solvent, such as a tool, is added to the fermentation liquid to flocculate the potassium form of the gum, which is then recovered by centrifugation or other solid/liquid separation techniques.Further dissolution, reprecipitation and washing steps are typically Thus, the heteropolysaccharide produced by Xanthomonas no2cutilia for carbohydrates is
It is usually obtained as a pale yellow, thick, viscous solution.

Xanthan gum is a common and widely used suspension and viscosity forming agent. Some of its special uses are oil well fluids,
Found in paints, sprays and cleaning fluids. However, xanthan gum has slight drawbacks. Hydration can occur since it is extremely difficult to disperse and wet in water or fermentation liquor. A high degree of shear is usually required to wet each rubber particle. Once dispersion and wetting is achieved, hydration of the rubber is extremely rapid as evidenced by an increase in viscosity. Xanthan gum and guar exhibit very different rheological properties and have different molecular configurations and are obtained from different sources.

For example, for dilution to the desired solids content and for bleaching of textiles or wood products, they can be easily stored, even if subjected to vibrations during tank car or tank truck transport, for example to textile factories or wood products factories. There is a need for stable dithionite hydrosol compositions with pseudoplastic properties that can be easily pumped when delivered to a storage tank for short-term storage until needed, such as for It clearly exists. However, attempts in accordance with the present invention to use both guar gum and xanthan gum as suspending agents for sodium dithionite crystals have shown that even during static storage, these gums surprisingly produce slurries that can gel or settle together. proved to have an unpredictable tendency to form.

SUMMARY OF THE INVENTION Accordingly, the subject of the invention is a hydrosol containing dithionite crystals which can be suspended during long-term storage and transport and, if necessary, can be easily pumped. An object of the present invention is to provide a method for producing a stable dithionite slurry.

It is also an object to provide a storable and pumpable dithionite slurry as a novel composition using xanthan gum as its suspending component.

The fermentation of carbohydrates for the production of biosynthetic water-soluble xanthan gum by the action of Xanthomonas ζcutilia is well known. The first research in this field was conducted by the US Department of Agriculture and was published in US Pat.
It is described in the specification of No. 0. Particularly well known is Xanthomonaa campestris for glucose substrates.
s) Effect of NRLLB-1459.

Xanthomonas hydrocolloid P (i.e., xanthan gum) is prepared by transferring Xanthomonas campestrisno ζcutilia to a suitable medium and conditioning it for growth in two steps before growing it in a final medium containing triglucose. Manufactured. After 96 hours at 3° C. with proper aeration and stirring, a Xanthomonas hydrocolloid is produced at a concentration of approximately 1.

Xanthomonas campestris is a nonoctilia selected for the purpose of producing biosynthetic Xanthomonas hydrocolloid P;
), X, malvacearum
), X, carotenase
), X, Incanae (1ncanae), X, phaseoli, X, Pesicatoria (v
esica-tOria), X, A no ξ periodicola (
papaveriocola).

X,)u7 X /I/sense (translucen)
a), X.

J vasculorum, and X
- Other Xanthomonas species can also be used, such as Hedrae (h@drae).

US Pat. No. 3,391,060-US Pat. No. 3,391,061;
Same No. 3427226; Same No. 3455786; Same No. 3
No. 565763; No. 3966618; No. 4094
No. 739; No. 3773752; No. 4051317
No. 4135979; No. 4296203; No. 3919189; No. 3119812; No. 33
No. 16241; No. 4282321; No. 42998
Specification No. 25, "Encyclopedia of Chemical Technology"
Chemical Technology), 3rd
Edition, (1980, John Wiley & 5on
There are a number of patents and publications describing the production of xanthan gum, including No. s, pp. 62-64), the contents of which are cited herein.

Xanthan gums of various companies with slightly different molecular structure and rheological properties, produced from X.
Keleo Company's trademark "Kelzan" or "6Keltrol" (
Keltrol); Pfizer Chemical Division
on) Trademark 1 Flocon” (Rhone-Poulenc)
Trademark "Rhodopol 23";
Meer Corpora
Trademark of Merezon
) 8” and “Mere-tec 3”
Available from several manufacturers including 0'' as well as other manufacturers.

For example, the widely used xanthan gum produced by culture fermentation with the microorganism Xanthomonas campestris and sold under the trademark Kelzan as industrial xanthan gum by Kelco, a subsidiary of Merck and Company. The polysaccharide that can be used has a moisture content of 12 degrees, an ash content of 10%, a specific gravity of 1.6, and a content of 52.414/ft.
It is a dry, cream-colored powder with a bulk density of 3 (approximately 0.8417 cm5), a nitrogen content of 1.2 and a mesh size of 4.0. As a solution in distilled water, its - is 7.0 and its surface tension is 75 dynes
/cm, its viscosity is δ50 cP as measured with a Prützfirr LVF viscometer at 60 rpm, and its freezing point is 0.0°C.

Another solid xanthan rubber manufactured by Kelco under the trade name 9C57 has rheological properties of high viscosity at low concentrations, pseudoplastic flow over a wide range of shear rates, and a significant yield point.

Such characteristics indicate that xanthan rubber molecules have a strong molecular structure. Very low shear rate (1 Se
(below 1), this modified xanthanthanum rubber exhibits a more Newtonian flow than the Kel/tan rubber. As a solution in distilled water, its range is from 6 to
8 and its viscosity is 630 to 1000 cP.

A whole xanthan fermentation solution with a viscosity in the range of 3500-4500 cP, easily pumped or injected, and with a significant yield point at biopolymer concentrations above 0.1% is 13.81 or Flocon Biopolymer from Pfizer Chemical Company at a biopolymer concentration of 3.7.
Available as 4800. This material is covered by U.S. Pat.
No. 119546, the contents of which are incorporated herein by reference. The aqueous fermentation liquor is believed to be produced by variant strains of Xanthomonas campestris. It is protected with formaldehyde and does not exceed a 1.5% concentration of unreacted sugar. It is a gelatinous liquid with a yellow-brown appearance. It has a higher apparent content of active purified carbohydrates than commercially available solid xanthan.

Since the 70 Con 4800 solution is highly pseudoplastic in nature, the viscosity that decreases when exposed to high shear is completely restored when the solution is returned to a low shear condition. The solution viscosity of this biopolymer is not affected by - within the range of 5 to 12.

It is clear that any and all forms of xanthan gum can be used in the present invention to provide a slurry that does not contain alkali tripolyphosphates, such as sodium tripolyphosphate. Only if the tolipo IJ 17 phosphate is present, certain changes must be made, as described below.

Generally, the suspendable, injectable and pumpable tripolyphosphate-free dithionite slurry (0.25% xanthan content): lOOpon)' (approximately 4
It can be manufactured using as little as 0.25 pounds (approximately 0.11 kg) of tantan rubber. This amount is equivalent to 1 pound of xanthan (approximately 0.4
Approximately 146 bottles of commercially available hydrosulfite per 5 kg) 1″
(approximately 65.7 kg). The slurry is non-settling and completely pourable at any desired solids content within the practical range imposed by slurry viscosity. Such a slurry, for example, is easily flowable and has a
Easily injected and pumped with viscosities up to P.

However, by allowing a slight sedimentation, 0
．． A soft and dispersible settled slurry is obtained containing a small amount of xanthan gum, on the order of 20%. Such partially suspended but dispersible slurries are useful for many purposes, such as for relatively short distance transportation. This amount equates to approximately 182 pounds of hydrosulfite per pound of xanthan gum, including, for example, 36.4 parts dorosulfite and 0.20% xanthan gum. Slurry can be mentioned.

Advantageously, since the slurry contains at least about 20% hydrosulfite, chelate and alkali, the slurry has a pH of at least about 10.

A suitable alkali is sodium hydroxide. This is particularly advantageous over soda ash since it requires a deposit (in Durham equivalent) such as potassium hydroxide or soda ash.

A method for producing a storable and pumpable slurry from commercially available hydrosulfite is, by weight, (a) producing a hydrosol as a 1% aqueous solution of xanthan gum; (b) stirring an appropriate amount of this xanthan solution into water; xanthan gum in the final product is approximately 0.13
~0.25 wt% 1C is 5KL; (C) While stirring the above solution, add an aqueous solution of the chelate and 5KL.
(d) cool the resulting solution to a temperature below 45°F (about 7.2°C) in an ice bath; and (a) add anhydrous hydrosulfite to the cooled solution. Na2S2O4 (commercial grade) 28 at a rate to maintain its temperature below 45°F (about 7.2°C) and
36% and having a pH of at least 10.

When the slurry is used for fabric bleaching, it advantageously contains, by weight, at least about 36% commercially available sodium dithionite, at least about 3% sodium hydroxide as alkali, at least about 0.25% mixed chelate, and Consists of at least about 25% xanthan gum, such as Kelsan grade. The viscosity is in the range of 6000-8000 cP. Total (although obviously smaller amounts (e.g. 20% pure) of dithionitite/acid salts can also be used;
The ranges mentioned above are advantageous.

When the slurry is used for wood bleaching, the slurry additionally contains at least about 3% by weight of IJum and about 2% by weight of sodium tripolyphosphate (see U.S. Pat. No. 3,985,674). . The disclosure of that US patent is incorporated herein by reference. For example, the chelate is the tetrasodium salt of ethylenediaminetetraacetic acid and is at least about 0.08% by weight of the slurry.

It is clear that difficulties arise when sodium tripolyphosphate is present, for reasons that are not entirely clear. As previously mentioned, all forms of xanthan gum can be used to produce tripolyphosphate-free slurries. However, if tripolyphosphate is present,
All forms of xanthan can be used in one data example,
Two forms of xanthan are available in all data examples. Two widely applicable forms of xanthan are the previously mentioned ``9C57'' and 7Flocon 4800''.

In fact, when using these two forms of xanthan gum, it can be present in concentrations as low as 0.13 weight factor.

One data example that all forms of xanthan gum can be used is commercially available sodium dithionite 28 wt 5, Na
5P301o O,17 Weight 5, Na2CO33,28
~3.29% by weight, 0.78% by weight, 0.78% by weight, and 0.08% by weight of water.

Example pure Na2S2O488~8 Q % C”F uniform content t
Experiments utilizing formate-derived sodium dithionite (F/hydrosulfite) to produce a storable and then pumpable dithionite slurry with t'. In a number of experiments, F/hydrosulfite was used as an ingredient in two types of commercially available bleaching products.
(1) a textile bleaching system and (2) a wood pulp bleaching system (both of which are registered mixtures). These slurries are 32-40
It is stable for at least 3 weeks during storage at temperatures ranging from 0 to about 4.4°C. The physical properties of the slurry are: Textile Slurry Wood Pulp Slurry Density
1.4P/Go 1.1/Door PH1310~11 Appearance White White viscosity 6000~8000 CPS 3000~4
000 CPS freezing point 17-18 below 16-1
7〒 (approx. -8,3 to approx. -7,8℃) (approx. -8,9 to approx. -8,3℃) Ax Seisert (5aybolt) viscometer The laboratory stirrer used in these experiments was a Schiffai
Mixer Kannozoni (Jiffy MixerCo)
mpany) Inc (Irvine)
), California (California)] was the H8 type.

Examples 1-B Attempts to produce a dinitrous/acid slurry that does not settle, gel, and produce unpumpable shipping materials were conducted using eight materials with thickening or charge repulsion properties at 35% F. /hydrosulfite to a slurry of dithionite containing hydrosulfite. All of these slurries were observed to be insufficient as listed in Table 1.

Examples 14-23 Experiments were now conducted using guar gum as a suspending agent in two types of F/hydrosulfite slurries that are commercially available as bleach systems. Examples 14-19 used fabric bleaching types and are listed in Table 1. Examples 20-23 used a wood pulp bleach type and are listed in Table 1. In both tables, "% F/Hydro" indicates the weight ratio of formate-derived sodium hydrosulfite used in the slurry. As noted in these two tables, none of the guar thickened slurries were satisfactory as easily confirmed by observation.

Examples 24-36 Firstly, a solution of kerzanxanthan gum in water was prepared in Example 2.
4-26 and 29-35. The appropriate weight of this solution was added to a predetermined amount of water, followed by the addition of alkali and chelate. Alkali is 50% NaO
It was in the shape of an H.

The chelate is the sodium salt of ethylenediaminetetraacetic acid (EDTA) or is available from Organic Chemicals Division of W, R., Brace & Company.
n of W, R, Grace and Compa
A liquid mixture of chelating agents is commercially available from Hampen Co., Ltd. (located in Nashua, New Hampshire).
pen) -0H.

The solution was cooled to 32'F (OC)K and the solid F/hydrosulfite was added at a rate such that the temperature was maintained at below 40-45°C. Ta. Next, the slurry was returned to the cooling bath, and its fluidity etc. were examined for 3 days.

The use of xanthan gum at various levels in textile bleaching slurries is shown in Table 3. Parts by weight of 1% xanthan solution are stated as parts by weight of xanthan gum for each example. Although the full flow of Example 24 is advantageous, the slight settling and flow of Examples 25 and 26 may also be advantageous for some applications, especially for conveying conditions involving relatively mild vibrations or short periods of transport. Suitable examples 27 and 28 are xanthan gum (Kelzan
grade) was prepared by dissolving it in 21% of the total amount of water and used to make the hydrosol. The NaOH solution and chelate were then added to the remaining amount of water and the mixed solution was cooled to about 35°C. Then, add 4% of crystalline F/hydrosulfite (88% Na2S2O4)
Co5tic while cooling to maintain a temperature of 5°C.
added to the solution. A hydrosol was added to this aqueous slurry to produce a stable slurry that did not settle within 3 days. After storage for 2 days at about 35°C, the slurry of Example 27 has a 7.120
The slurry of Example 28 had a viscosity of 7.980 cP.

Examples 29-36, along with Examples 24-28, demonstrate that all forms of xanthan gum can be used. Example 29 is Kelzan-M, Examples 30-32 are Keldef-3, and Example 35 is 9C57 (all Kelco
) was used.

Examples 33 and 35 Hough o -t y (FLOCON
) (3,7%) and Examples 34 and 36 are Flocon (
13.84%) (both five-(Pfizer
) was used.

Examples 37-48 Next, commercially available sodium hydrosulfite (
88-89 purity) can be used to make a pumpable slurry with xanthan gum, but guar cannot be used at all. The results are shown in Table ■.

Compositions Containing Tripo IJ IJ Phosphate As shown in the table, compositions containing Pol IJ phosphate show variable results with the exception of Phizer's Flocon or Kelco's 9C57. However, with the exception of one data example in which all forms of Kelsan rubber can be used. The following example illustrates this.

Examples 49-65 Experiments for producing storable and pumpable slurries for use as wood pulp bleaching systems Examples 48-63
The process consists of making a 1% aqueous solution of Kelsan gum and then adding an appropriate amount of this solution to water. The next additions to the water were a solution of sodium carbonate, sodium tripolyphosphate, chelate and then 50 part Na0
f (solution). The entire solution was then incubated at 32'F in an ice bath.
(0°C). The required amount of solids (crystalline F/hydrosulfite) was added at a rate to maintain the temperature below 45'F. The slurry was then cooled again in an ice bath for 3 days and observed for separation, sedimentation, and pourability.

Examples 64 and 65 are similar to Examples 27 and 2δ, in which xanthan gum is dissolved in 12% of the total amount of water to create a hydrosol, and then Na2CO3, Na5P3O10,N
Prepared by adding aOH solution and chelate. The solution was then cooled to about 35°C. solid crystalline F
/hydrosulfite was added with cooling to maintain a temperature of 45°C. To this aqueous slurry, xanthan hydrosol was added to produce a stable slurry that did not settle after 3 days of storage. The slurry of Example 64 had a density of 1.37 f/ml and a viscosity of 39QQcP. The slurry of Example 65 had a viscosity of 4040 cP.

The following example in Table ■ shows the critical mass of xanthan concentration, all observations were made after 3 days in an ice bath, and all percentages are by weight (corrected for impurities in F/hydrosulfite). none).

As an average value, correcting for impurities in the F/human day sulfate by multiplying by 0.885, the amount of pure Na2S2O4 in the F/hydrosulfite of the example is: 27 23.9 28 24, 8 30 26, 631
27.436.4 32
．． 2 As can be seen, only Examples 41, 63 and 64 produced acceptable results.

Examples 66-70 The next two examples in Table ■, along with wood pulp slurry,
Example 66 shows the use of Phizer's Flocon Biopolymer 480o as a 13.8% Flocon fermentation solution with 0.19% xanthan and a 3.7% Flocon fermentation solution in Example 67, both of which are F/hydrosulfite. It was made of.

The experiments using 9C57 xanthan gum, listed as Examples 68-70 in Table II, illustrate the use of this xanthan in wood pulp slurries that normally coagulate or are unstable in some way with Kelsan gum. 2 from the end
The ratio in the column is sodium triphosphate (A) a
sPsOl.

The total number of moles of (expressed as) + the number of moles of N & 2CO3 is 10
Ideally, this ratio should be approximately 4.0 + 1-0.2 for the use of Kelsan. Deviations above and below this ratio require the use of K9C57 or Flocon biopolymers.

On a weight basis, biopolymer fermentation fluid ranks 9% in its ability to create satisfactory storage and pumpability.
C57, which is approximately equivalent to commercially available solid xanthan.

Claims (1)

Claims: 1. A storable product consisting essentially of at least about 20% by weight of pure sodium dithionite, at least about 0.20% by weight of xanthan gum, chelate, alkali and water and having a pH of at least 10; Pumpable, tripolyphosphate-free aqueous slurry. 2. The slurry of claim 1, wherein the slurry is at least 25% by weight of pure sodium dithionite. 3. at least about 20% by weight of sodium dithionite;
The slurry of claim 1 containing a chelate, an alkali, and at least about 0.13% by weight of xanthan gum, which is commercially available product K9C57 (Kelco) or Flocon 4800 (Phizer), and having a pH of at least 10. . 4. Mainly commercially available sodium dithionite 28% by weight
, xanthan rubber 0.17% by weight, Na_5P_3O_
1_01.92% by weight, Na_2CO_33.28-3
．． 29 by weight 5, 0.78% by weight sodium hydroxide and 0.08% by weight chelate and water. 5. Commercially available sodium dithionite, sodium tripolyphosphate, sodium carbonate, chelate, and xanthan gum produced by bacteria of the species Xanthomonas campestris, with the number of moles of 100% Na_2S_2O_4 added to the number of moles of sodium tripolyphosphate + The quotient divided by the sum of the moles of sodium carbonate is below or above the range of 3.8 to 4.2, and the xanthan rubber is a commercial product K9C57 (Kelco) or Flocon 4800 (Phizer). A storable and pumpable aqueous slurry. 6. In the process of preparing a storable, pumpable, tripolyphosphate-free aqueous slurry of dithionite from crystalline dithionite, (A) from about 0.20 to xanthan gum to the final product;
A dilute hydrosol containing 0.25% by weight is prepared; (B) an aqueous solution of the chelate and sodium hydroxide or potassium hydroxide is subsequently added to the dilute hydrosol while stirring the dilute hydrosol to form an alkaline hydrosol; (C ) Alkaline hydrosol in an ice bath at approximately 45°F (7°C
) to form a cold hydrosol; and (D) adding commercially available sodium dithionite to the cold hydrosol at a rate such as to maintain the temperature below 7° C. and at least about at least about 30% pure sodium dithionite. A method for making a storable and pumpable aqueous dithionite slurry, characterized in that it is added in an amount sufficient to obtain a dithionite slurry containing 25% and having a pH of at least 10. 7. The method of claim 6, wherein the hydrosol of step A is added to a commercially available slurry of sodium dithionite as a final step. 6. The method according to claim 6, wherein the concentrated hydrosol is prepared as a 1% aqueous solution of xanthan gum, and the concentrated hydrosol is added to water with stirring to form a dilute hydrosol. 9. The slurry is approximately 36% commercially available sodium dithionite.
, at least about 3% sodium hydroxide or potassium hydroxide, at least about 0.25% chelate, and at least about 0.25% xanthan gum. . 10. In the process for producing a storable and pumpable aqueous slurry of dithionite from crystalline dithionite, (A) the final product is treated with commercially available product K9C57 (Kelco) or Flocon 4800 (Phizer). A dilute hydrosol containing about 0.13 to 0.25 wt. (C) The alkali hydrosol was heated to 32°F (0°C) in an ice bath.
) to form a cold hydrosol; and (D) adding commercially available sodium dithionite to the cold hydrosol at a rate to maintain its temperature below 7° C. and at least about 25% pure sodium dithionite. A process for making a storable and pumpable aqueous slurry, characterized in that it is added in an amount sufficient to obtain a dithionite slurry containing and having a pH of at least 10. 11. The method of claim 10, wherein the hydrosol of step A is added to a commercially available slurry of sodium dithionite as its final step. 12. The method according to claim 11, wherein the dilute hydrosol is produced by preparing a concentrated hydrosol as a 1% aqueous solution of xanthan gum and adding the concentrated hydrosol to water while stirring. 13. The slurry is a wood pulp bleaching composition, and step B
13. The method of claim 12, wherein the solution of sodium carbonate and sodium tripolyphosphate is additionally added to the dilute hydrosol sequentially with stirring.