Suncor, Inc.

Raymond N Yong

Amar J Sethi

Modified starch compositions and their use for flocculating mineral waste residues, particularly the red mud containing alumina liquors from bauxite residues, comprising the addition to an alumina liquor of a flocculating amount of a methylated starch which, optionally, may be hydrolyzed, or a methylated starch which is also sulfonated and, optionally, may be hydrolyzed. Preferably, the methylated starch compositions are potato and dasheen starch derivatives prepared at temperatures of about 50.degree. to about 85.degree. C.

Methylated starch compositions and their use as flocculating agents for

Certain yam starches hydrolyzed in the presence of insoluble metal salts formed in situ are surprisingly effective flocculants for destabilizing dilute as well as thick sludge suspensions and are particularly effective when used in the treatment of bituminous tar sands tailings and in phosphate slimes.

Hydrolyzed yam starch flocculants

Cassava starch hydrolyzed in the presence of insoluble metal salts formed in situ is a surprisingly effective flocculant for destabilizing dilute as well as thick sludge suspensions and is particularly effective when used in the treatment of bituminous tar sands tailings and in phosphate slimes.

Hydrolyzed cassava starch flocculants

Dasheen starch hydrolyzed in the presence of insoluble metal salts formed in situ is a surprisingly effective flocculant for destabilizing dilute as well as thick sludge suspensions and is particularly effective when used in the treatment of bituminous tar sands tailings and in phosphate slimes.

Hydrolyzed dasheen starch flocculants

A process for making an improved starch flocculant by heating an aqueous dispersion comprising about 4 to about 12% starch solids, lime and alum until maximum vicosity is obtained, adding a metal salt and finally effecting hydrolysis by additional heating.

Process for making starch flocculants of improved efficiency

Destabilization of sludge with hydrolyzed yam starch flocculants

Destabilization of sludge with hydrolyzed cassava starch flocculants

Destabilization of sludge with hydrolyzed dasheen starch flocculants

A method for estimating the content of clay or clay minerals in the tailings or sludge resulting from the extraction of bitumen from tar sands and similar materials by titrating the tailings or sludge with methylene blue.

Method for determining clay content in tailings and sludge

Tailings from an oil sands hot water process extraction plant are mixed with hydrolyzed starch flocculant and transferred to a settling pond. After a residence period on the order of one year, sludge from the lower region of the settling pond is withdrawn, mixed with a hydrolyzed starch dewatering agent and transferred to a collecting pond. After a residence period on the order of one week, partially dewatered sludge is withdrawn, mixed with sand, and deposited in a terminal disposal area, the sand in the mixture there effecting an internal surcharge to obtain further dewatering. The hydrolyzed starch additives are obtained by the aqueous hydrolysis of a starch in the presence of one or more metal salts.

Method for treating oil sands extraction plant tailings

Carbonates and bicarbonates are removed from the sludge of tar sands tailings ponds whereby solids settle from the sludge more rapidly than in the presence of the carbonates and/or bicarbonates. Hydrolyzed starch is used as a flocculant in the process and alcohol may also be used to assist in the settling and/or to improve the characteristics of the settled sludge for subsequent dewatering.

Decarbonation of tailings sludge to improve settling

Bitumen content of tailings or sludge obtained from processing of tar sands is quickly determined by a two step process wherein (1) clay mineral content is determined by adsorption of methylene blue and this value correlated to adsorbed organic material, (2) the content of total organic material is determined by a chromic acid oxidation, and the difference in these values gives the bitumen content.

Rapid method for bitumen analysis

In order to compress the sludge layer of an industrial process tailings pond, in a naturally occurring fines-containing body of water, beyond the density which it will naturally reach after treatment by the addition of a specific hydrolyzed starch additive, sand is distibuted over the sludge layer as a water permeable surcharge which, by weight, further compacts the sludge to obtain additional dewatering. The hydrolyzed starch additive is selected from a specific family and provides improved shear strength and permeability characteristics to the sludge layer such that it can support the sand surcharge.

Method for dewatering the sludge layer of an industrial process tailings

A tailings pond sludge layer of high density and strength is obtained by treating the sludge with an additive selected from a specific family of hydrolized starch additives which impart improved permeability and shear strength characteristics to the sludge. Thereafter, the sludge is mixed with sand which adds self-weight whereby further dewatering of the sludge sand mixture is accomplished. Unlike untreated sludges or sludges treated with other known additives or flocculants, sludge treated with the aforementioned hydrolyzed starch additives is able to support the sand.

Treatment of tailings pond sludge

Hydrolyzed wheat, corn, and potato starches are effective flocculants in destabilizing dilute as well as thick sludge suspensions. These starches are equal to, or better than, the synthetic polyacrylamide flocculants in destabilizing sludge suspensions, particularly when used in the treatment of bituminous tar sands tailings. The hydrolyzed wheat starch is especially effective when first contacted with metal salts such as salts containing calcium, aluminum and phosphate ions, and most particularly when first treated with a combination of such salt, formed in situ, and a lower aliphatic alcohol. Among the potato starch flocculants which were found to be generally better than the corn starch flocculants, those containing AlPO.sub.4 were the best. Potato starch flocculants are equally effective on oil-removed and no-oil-removed sludge suspensions. It also has been found that when cement is added together with the aforedescribed composition, there is achieved improved permeability and shear strength of the resulting sludge.

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Beaconsfield, Canada

Raymond N Yong