US2426140A - Nonsettling mineral fillers - Google Patents

Description

Patente d'Aug. 19, 1947 UNITED STATES PATENT OFFICE nonsn'rrrmo MINERAL FILLERS Armand R. Bollaert, Palos Verdes, Calif., assignor to Great Lakes Carbon Corporation, a corporation of Delaware No Drawing. Application October 15, 1945, Serial No. 522,477

8 Claims. (01.106-288) This invention relates to the treatment of mindiate layer of slurry of variable consistency, and

a hard and compact bottom layer. In extreme cases, as after long standing, the intermediate layer may be missing.

If the hard lower layer can be prevented from forming, the partial sedimentation which produces a concentrated slurry is harmless as this slurry, even if very thick, may readily be redispersed by simple stirring. The formation of a hard layer, however, is highly objectionable. Such sediments, formed in a stored package, are tedious and diflicult to again bring into suspension and are likely to result in lumping. Where such hard layers form in mixing vessels or tanks the apparatus may have to be cleaned out before it can again be put into operation. 1

I have discovered that the formation. of compact settled layers may be prevented, and sedimentation restricted to the formation of a thick slurry, by mixing with the filler a small proportion of a highly colloidal clay, such as the socalled bentonite, together With a minute proportion of a salt of ammonium with a mineral acid. These admixtures do not prevent sedimentation of the filler but, when used in suitable proportions, they maintain the settled layer in the soft and uncompacted condition in which it may readily be redispersed.

In order to determine the effectiveness of the treatment, the optimum dosages of the agents and the specific ammonium salts most efiective for the purpose, experiments were conducted with a diatomaceous earth filler consisting of the fines from the manufacture of high quality filter-aids by calcination with fiuxing agents. This material settles rapidly from aqueous suspension to form hard layers which are very dilficult to bring back into suspension.

In these experiments, grams of the filler was dispersed in 100 ml. water, with or without the addition of one or more of the agents named in the table below. The suspensions were then allowed to stand undisturbed for eight days, after which an arbitrary measurement of the solidity of the settledlayer was made by allowing a glass rod of 4' diameter and weighing 46 grams to subside to constant level through it. As the diameters of the cylinders in which the tests were made varied slightly, the measurement made was of the percentage of the total volume occupied by the layer sufiiciently solid to support the rod. As this figure is entirely arbitrary and useful only for comparison, numerous check experiments were made which showed that if this supporting volume did not exceed 14% of the total volume the settled layer could be redispersed without material dimculty, and that the difiiculty experienced in redispersion increased as this percentage volume increased.

Ammonium chloride and Wyoming bentonite were added to this suspension in the proportions set forth below, withthe following results:

Table 1 Composition in Grams Volume of Supporting Filler Bentonite Chloride Layer Per cent 10 l. O 0. 1O 0 10 1. 0 0. 06 11 10 1. 0 0. 05 16 10 1. 0 O. 04 16 1O 1. 0 0. 03 18 10 1. 0 0.02 18 10 1. 0 0. 00 l8 l0 0. 0 O. 00 21 10 l. 5 0. 06 0 10 l. 0 0. 06 l1 10 0.8 0.06 21 10 0. 6 0.06 21 10 0. 4 O. 06 21 10 0. 0 0. 06 21 It will be noted that these percentage figures are good only for this particular filler and do not show the same critical limits when other fillers are substituted for diatomaceous earth.

When other ammonium salts were substituted for the chloride, in constant proportions, the following results were obtained:

Table 2 Composition in Grams Volume Ammonium Salt of Sup- I Used porting Filler Bentomte Salt Layer Per cent 10 1. 0 0. 05 Sulfate 0 10 1.0 0. 06 Chloride. ll 10 1. 0 0. 06 Phosphate 14 10 1. 0 0. 06 Acetate 17 10 1. 0 0.06 Carbona 19 10 1. 0 0. O6 Oxalate... 19 10 l. 0 0.06 Hydroxide.-.- 20

The figures in these two tables show that neither bentonite alone nor the ammonium salt alone produce any material improvement in permanence and that they function together to produce the desired result. They also indicate a satisfactory stabilization of the suspension when the bentonite component is about 10% of the weight of filler taken and the ammonium chloride about 1%; of 1% of that weight. They also show perfect suspension when ammonium sulfate is substituted for the chloride in the above proportions, or when the proportion of chloride is raised to about 1% (with bentonite) or when the proportion of bentonite is raised to about (-with 0.6% chloride). Finally, they indicate that satisfactory results are obtained only in the use of the ammonium salts of the strong mineral acids such as hydrochloric, sulfuric and phosphoric.

I claim as my invention:

1. A stabilized aqueous suspension of finely comminuted diatomaceous earth containing from 10 percent to 15 percent of a colloidal bentonite and from 0.6 percent to 1.0 percent of an armmonium salt of a strong mineral acid, said percentages being on the dry weight of earth in said suspension.

2. A stabilized aqueous suspension of finely comminuted diatomaceous earth containing from 10 percent to 15 percent of a colloidal bentonite and from 0.6 percent to 1.0 percent of ammonium chloride, said percentages being on the dry weight of earth in said suspension.

3. A stabilized aqueous suspension of finely comminuted diatomaceous earth containing from 10 percent to 15 percent of a colloidal bentonite and from 0.6 percent to 1.0 percent of ammonium sulfate, said percentages being on the dry weight of earth in said suspension.

4. A stabilized aqueous suspension of finely comminuted diatomaceous earth containing from 10 percent to 15 percent of a colloidal bentonite and from 0.6 percent to 1 percent of ammonium phosphate, said percentages being on the dry weight of earth in said suspension.

5. A mineral filling and bodying agent characterized by settling from aqueous suspension to form a oft and readily dispersi-ble mass, consisting substantially of 100 parts of finely comminuted diatomaceous earth, from 10 parts to 15 parts of a colloidal bentonite, and from 0.6 part to 1 part of a salt of ammonium with a strong mineral acid, all said parts being by dry weight.

6. A mineral filling and bodying agent characterized by settling from aqueous suspension to form a soft and readily dispersible mass, consisting substantially of parts of finely comminuted diatomaceous earth, from 10 parts to 15 parts of a colloidal bentonite and from 0.6 part to 1 part of ammonium chloride, all said parts being by dry weight.

7. A mineral filling and bodying agent characterized by settling from aqueous suspension to form a soft and readily dispersible mass, consisting substantially of 100 parts of finely comminuted diatomaceous earth, from 10 parts to 15 parts of a colloidal bentonite and from 0.6 part to 1 part of ammonium sulfate, all said parts being by dry Weight.

8. A mineral filling and bodying agent characterized by settling from aqueous suspension to form a soft and readily dispersible mass, consisting substantially of 100 parts of finely comminuted diatomaceous earth, from 10 parts to 15 parts of a colloidal bentonite and from 0.6 part to 1 part of ammonium phosphate, all said parts being by dry Weight.

ARMAND R. BOLLAERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,016,892 Clarvoe Oct. 8, 1935 2,266,793 Opperman Dec. 23, 1931 1,738,967 Sadtler Dec. 10, 1929 1,758,145 'Clutterbuck Ma 13, 1930 2,366,047 Ner-linger Dec. 26, 1944 OTHER REFERENCES Natural Mineral Paint Extenders, by Charles T. Harness.

National Paint Bulletin, June 1945, page 6.