JPS626876B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel hydrolyzed wheat, corn or potato starch compositions and methods of making and using the same. More particularly, this invention relates to the discovery that hydrolyzed wheat, corn, and potato starches are effective flocculants for destabilizing dilute and thick sludge suspensions. Generally, these suspensions contain either clay minerals or metal oxide-hydroxides produced in large quantities during mining operations in the recovery of materials such as coal, bitumen and metals from tar sands. It is an aqueous colloid suspension. In metal mining operations, a suspension known as slime is formed, typically phosphate slime or similar materials produced in copper, nickel and titanium mining. In coal and tar sands mining, for example, mining effluent typically contains dilute or thick clay mineral suspensions. In order to properly dispose of these large amounts of mining effluents, regardless of their source, flocculants can destabilize these suspensions, thus allowing effective separation of water from solids. It has been used conventionally. In particular, in one aspect, the present invention relates to the treatment of tailing pond water obtained from a hydrothermal process for the treatment of bituminous sands such as Athabaskatar sand, and more particularly to the treatment of tailing pond water discharged from said process. The present invention relates to the treatment of water and clay-containing effluents with hydrolyzed wheat starch. In yet another aspect, the present invention relates to the treatment of phosphate slime commonly obtained in phosphate mining operations. Tar sands (also known as oil sands and bituminous sands) are placer deposits impregnated with thick, viscous petroleum. Tar sands are often found around the world in the same geographic areas as regular oil. The largest deposits, and the only one currently of commercial importance, are in the eastern Athabasca area of Alberta, Canada. This deposit is believed to contain over 700 billion barrels of bitumen. For comparison, this is roughly equivalent to the world's conventional oil reserves, 60% of which are found in the Middle East. Athabaskatar sand is a ternary mixture of bityumen, minerals and water. Bityumen is valuable and tar sands are mined and processed for its extraction. Bityumen content varies, averaging 12 percent by weight of the deposit, but ranging from 0 to 18 percent by weight. Water is typically 3 to 6 percent by weight of the mixture, increasing with decreasing bitumen content. Mineral content is relatively constant, ranging from 4 to 86 percent by weight. Several basic extraction methods have been known for many years to separate bityumen from sand. In the so-called cold water process, separation is achieved by mixing the sand with a solvent capable of dissolving the bitumen components. The mixture is then introduced into a large amount of water, water to which a surfactant has been added, or a neutral salt solution in water. The combined material is then subjected to pressure or gravity separation. The hydrothermal process for initially extracting bityumen from tar sands consists of three main process steps (the fourth stage, the final extraction, is used to clean the recovered bityumen for downstream processing). In the first step, called conditioning, the tar sands are mixed with water and heated directly with steam to form a sludge with a solids content of 70 to 85 percent by weight. Sodium hydroxide or other reagents are added as required to maintain the PH in the range of 8.0-8.5. In the second step, called separation, the conditioned mineral mud is further diluted so that settling can occur. A lot of sand-
Size minors rapidly precipitate and are extracted as sand dregs. Much of the bityumen quickly floats (settles to the top) forming a cohesive mass known as froth, which is recovered by scooping the settling vessel. This stream, called the middlings drag stream, may be subjected to a third processing stage, or scavenging. This step provides for increased recovery of suspended bityumen and can be accomplished by conventional flotation. Particle size distribution of mineral particles is particularly important for hydrothermal operations and for sludge accumulation. The terms sand, silt, clay, and fines are
Used as a particle size indicator for siliceous materials that do not pass through a 325 mesh sieve, silt is a material that passes through a 325 mesh sieve but is larger than 2 microns, clay is a material that is smaller than 2 microns, and its size is Contains siliceous substances. Conditioning of tar sands to recover bityumen involves heating the tar sands/water charge mixture to processing temperatures (180° to 200°);
It consists of physically mixing the mineral mud to a uniform composition and consistency and consuming (by chemical reaction) the added caustic or other reagents. Under these conditions, the bityumen is removed from individual sand grains and incorporated into the mineral mud in the form of separate droplets of the same order of magnitude as the sand grains. The same processing conditions were also found to be ideal for achieving the peptization of the clay that occurs naturally during tar sands charging. Peptizing or dispersing refers to breaking up naturally occurring clay agglomerates to create a slurry of individual particles. Thus, during conditioning, large sections of clay particles are well dispersed and mixed throughout the ore mud. Those skilled in the art will therefore be aware that the conditioning process prepares this resource (biteumen) for efficient recovery during the next processing step, making it possible to prepare even the most difficult to handle clays in a tailing operation. It will be understood that The second processing step, called separation, is actually a bitumen recovery step (separation has already taken place during conditioning). The conditioned tar sands mud is sieved to remove rocks and tar sand and clay lumps that cannot be conditioned. Rejected material, ie, larger than the sieve size, is discarded. The sieved mineral mud is further diluted with water to facilitate the settling and flotation process. That is, balls of bitumen, essentially mineral-free, rise to the surface and form a cohesive mass of bubbles on the surface of the separation cell, while at the same time mineral grains, especially sand-sized minerals, settle to the bottom and form scum. removed from the bottom of the separation cell. The media in which these sinking and floating processes occur are called middlings. Midlings consist primarily of water with suspended particles of fine material and bitumen. The particle size and density of sand and bitumen particles are relatively fixed. The parameter that most influences the settling process is Midlings viscosity. When the fines content exceeds a certain threshold (threshold varies depending on the composition of the fines), characteristically the viscosity rapidly reaches a high value, with the result that the settling process essentially stops. Under these operating conditions, the separation chamber is said to be in an upset state. Almost no oil is recovered and all streams leaving the chamber have roughly the same composition as the feed. As the fines content of the charge increases, more water must be used in this step to keep the viscosity of the middlelings within a workable range. The third step in the hydrothermal process is scavenging. The fines content of the charge dictates the process water requirements due to the need to control Midlings clay, which is governed by the clay/water ratio as discussed above. To maintain the mass balance of the separation chamber, it is usually necessary to withdraw a drag stream of middlelings, which may be scavenged for recovery of incremental amounts of bitumen. Air flotation is an effective cleaning method for this Midlings flow. Final extraction or foam cleaning is usually accomplished by centrifugation. The foam from the first extraction is diluted with naphtha and the diluted foam is then subjected to two-stage centrifugation. This process produces an essentially pure (diluted) bitumen oil product. The water and minerals removed from the foam constitute an additional stream of debris that must be disposed of. Tailings in the nomenclature of the extraction process
is a substance that is generated during the process of extracting valuable materials from ore and must be discarded. In tar sands processing, tailings are the total tar sands ore plus the net addition of processing water, minus only the bitumen product recovered. Tar sand tailing can be subdivided into three categories. (1) Items that are too large to pass through the sieve, (2) Sand tailings (a category that settles quickly), and (3) Tailings sludge (a category that settles slowly). Anything too large to pass through the sieve is typically collected and then treated as a separate stream. Disposal of tailings is all the operations required to place the tailings in their final abandoned location. One obvious long-term goal of tailings disposal is to return them to the area from which they were excavated in a satisfactory manner. There are therefore two main modes of operation for tailings disposal. (1) Embankment construction - A method of mechanical compaction of sand tailing sections after transporting the tailings by water. (2)
Dumping in water - method of transportation by water without mechanical compaction. Recently, due to the high level of ecological awareness in Canada and the United States, technical interest in tar sands operations has begun to focus on tailings disposal methods. The concept of tar sand tailings disposal is simple. If we imagine that one cubic foot of tar sands was mined, this would leave a one cubic foot hole in the ground. The ore is processed for resource recovery and the remainder, which includes both process material and gangue waste minerals, constitutes tailings which are not valuable and must be disposed of. In tar sands processing, the primary treatment substance is water, and the gangue-free minerals are primarily sand, with some silt and clay. Physically, tailings consist of a solid part (sand tailings) and a part that is more or less fluid (sludge). The most satisfactory place to dispose of these tailings is of course an existing one cubic foot hole in the ground. However, the sand tailings from one cubic foot of ore alone were found to occupy approximately one cubic foot. The amount of sludge is variable depending on ore quality and processing conditions, but 0.3
It can be up to cubic feet. Tailings therefore cannot fit exactly into the original hole in the ground. The historical literature encompassing hydrothermal methods for bitumen recovery from tar sands has little to say regarding the recognition that a net accumulation of liquid tailings or sludge will occur. Great, near McMurray, Futto, Alberta;
The presence of sludge accumulation was anticipated based on analysis of Canadian, Oil Sands, and field test unit operations that led to the plant design. This accumulation came to be known as the "Pond, Water, Problem." Observations during the start-up and early commercial operations at McMurray, Hutt, were insufficiently accurate to confirm predictions. Since 1969, data from commercial operations have confirmed the accumulation of layers of fines and water (sludge) in the Great Canadian Oil Sands (GCOS) tailings disposal area. The above sludge settles very slowly and becomes dense after several years, if at all. For embankment construction at the GCOS plant, tailings are carried by hydraulic power to the disposal area, on top of a sandy embankment constructed to serve as an enclosure for the liquid sump contained therein. be thrown away. On the banks, the sand settles rapidly, and a slurry of fine powder, water, and a small amount of bityumen flow into the pond interior. The settled sand is mechanically compacted to build the embankment to a higher height. Slurry flowing into the pond begins to form layers as it settles over a time scale of months to years. As a result of this long-term settling, two layers are formed. The top 5 to 10 feet of the sump is a layer of relatively clear water containing 0 to 5 weight percent solids. Beneath this clear water layer there is a discontinuity in solids content. In just a few feet the solids content increases to 10 to 15 weight percent, after which the solids content increases regularly toward the bottom of the pond. Solids contents in excess of 50% by weight have been recorded in the deepest parts of the ponds. This second layer is called the sludge layer.
The solids content of the sludge layer increases regularly from top to bottom by a factor of 4-5. Clay in this layer -
The water ratio also increases, but with a lower factor of 1.5-2.5. The clay is dispersed during processing but apparently partially reagglomerated into a very brittle gel network. Through this gel, fine particles larger than clay slowly settle. Dumping is an operation in which tailings are dumped directly over the top of a sand bank into a sump. Rapid and slow settling processes occur, but the distinction is not as sharp as in embankment construction, and mechanical compaction is not carried out. The sandy portion of the tailings settles rapidly, forming a gently sloping beach that extends from the dump site toward the interior of the pond. As the sand settles, fines and water flow into the sump and begin settling over a long period of time. In summary: (1) Tar sands contain clay minerals. (2) In hydrothermal extraction, most of the clay is dispersed in the process stream, which traverses the circuit and exits into the tailings. (3) The amount of treated water added is determined by the clay content of the charge and the need to control the viscosity of the Midlings stream. (4) The amount of water required to control the viscosity of midlings is large compared to the amount of ore itself. (5) When disposed of, the clay settles very slowly and therefore the tailings treated water components are only partially available for reuse through recirculation. What cannot be recycled represents a net accumulation of tailings sludge. The pond water problem is therefore to devise long-term economical and ecologically acceptable means to remove, minimize, or permanently dispose of the accumulation of liquid tailings or sludge. Coagulation of drag streams to improve settling properties has been proposed and practiced in the prior art. In agglomeration, individual particles (in this case clay particles) are combined into rather loosely bound agglomerates or flocs (aggregated particles that can be considered as independent particles resulting from agglomeration). The extent of agglomeration is controlled by the probability of collisions between clay particles and their tendency to stick after collisions. Agitation increases the probability of collisions and the tendency to stick is increased by the addition of flocculants. As flocculants, reagents act by one or a combination of three general mechanisms. (1) Neutralization of electrical repulsion surrounding small particles. This allows Van der Waals cohesive forces to hold the particles together once they collide. (2) Precipitation of large flocs such as metal hydroxides that trap fine particles. (3) Cross-linking of the grains with natural or synthetic long chain high molecular weight polymers. These electrolyte polymers are believed to act by adsorption (through ester formation or hydrogen bonding) of hydroxyl or amide groups on solid surfaces, with each polymer chain supporting more than one solid particle in suspension. It bridges the gap. Among the various reagents that have been found useful in clay flocculation are the following: aluminum chloride,
polyalkylene oxides such as polyethylene oxide, calcium compounds such as calcium hydroxide, calcium oxide, calcium chloride, calcium nitrate, calcium hydrogen phosphate, calcium sulfate,
Calcium tartrate, calcium citrate, calcium sulfonate, calcium lactate, calcium salts of ethylenediaminetetraacetate and similar organic sequestering agents. Also useful are qua-flower or high molecular weight acrylamide polymers, such as polyacrylamide or copolymers of acrylamide and a copolymerizable carboxylic acid such as acrylic acid. Other flocculants that have been considered include acrylic acid or methacrylic acid derivatives, such as acrylic acid,
Polymers of methacrylic acid, alkali metal salts and ammonium salts of acrylic acid or methacrylic acid, acrylamide, methacrylamide, aminoalkyl acrylate, aminoalkylacrylamide, aminoalkylmethacrylamide and N-alkyl substituted aminoalkyl esters of acrylic acid or methacrylic acid is included. For those skilled in the art, the "pond water problem"
It will be appreciated that a satisfactory solution to the pond water problem must be economically as well as ecologically acceptable. Accordingly, one object of the present invention is to provide a flocculant that is effective in destabilizing dilute as well as thick sludge suspensions, particularly colloidal suspensions obtained from mining operations. It is another object of the present invention to provide an effective flocculant for treating tar sand tailing streams that selects suspended clay particles. It is another object of the present invention to provide such a flocculant that is economical to manufacture and use in treating both tar sands tailing streams and phosphate slimes obtained from phosphate mining operations. It is. It is a further object of the present invention to provide such a flocculant which is otherwise safe and easy to handle and which itself does not have any ecologically undesirable side effects. According to the invention, the above and other objects are achieved by using hydrolyzed wheat, corn or potato starch as a flocculant to destabilize dilute and thick sludge suspensions. It was found that this could be achieved. More particularly, when these starches are hydrolyzed in the presence of metal salts, compositions are formed that are highly effective in destabilizing such suspensions. More specifically, particularly effective agglomerated compositions are produced when _CaAlPO4 wheat starch is used in combination with lower aliphatic alcohols. AlPO ₄ potato starch can alternatively be used. As previously mentioned, the sludge treated in accordance with the present invention is an aqueous colloidal suspension containing either clay minerals or metal oxides, hydroxides formed during mining operations. For purposes of illustration and for reasons of simplicity only, the following description is set forth with respect to colloidal clay suspensions obtained from bituminous tar sands mining and phosphate oxide-hydroxide slimes obtained from phosphate mining. However, the present invention
It will be appreciated that all such destabilization of suspensions is directed generally. In accordance with the present invention, it has also been discovered that improved water permeability and shear strength of the resulting destabilized sludge is achieved when cement is added to the suspension in conjunction with the aforementioned composition. The invention, both as to how the flocculants are made and how they are used, will be best understood by reference to the description made in conjunction with the following drawings. The only figure in the drawing is a schematic representation of the hot water extraction process in which the present invention finds particular application. Referring now to the single figure, bituminous tar sand is fed into the system through line (tube) 1 and into a conditioning drum or attritor 18. Water and steam are introduced into the attritor through another line 2. The total amount of water introduced in liquid and vapor form is small based on the weight of the tar sands being treated. The water-conditioned tar sand passes through line 3 to a feed sump 19. This sump serves as a zone for diluting the sludge with additional water before the passage to the separation zone 20. Mineral tar sands are continuously flowed through line 4 from feed sump 19 into separator 20 . Since the stationary zone in the separator 20 is relatively stationary,
Therefore, the bityumen bubbles rise to the top and line 5
, while the sand bulk settles on the bottom as a layer of dross, which is removed through line 6 . The Midlings stream (sand mix) is taken out through line 7 for processing as described below. Compared to the stream withdrawn through line 7 , another relatively oil-rich midlings stream is withdrawn from the cell via line 8 to flotation scavenging zone 21 . Air flotation operations occur in this zone, resulting in the production of additional oil foam, which is transported from the scavenging zone to line 9.
The foam is mixed with the primary foam powder from the separator 20 and sent to a foam settling tank (foam sump tank) 22. The oil-lean water stream is removed from the bottom of the sweep zone 21 through line 10 for further treatment as described below. In the settling zone 22, some additional oil-poor water is extracted from the foam and removed through the line 11 to form a flow of oil-poor water from the flotation sweep zone, a flow of sand from the separation zone, and a flow of sand from the separation zone. It is mixed with a portion of the lower middle layer taken out from the separator. Bitumen from the sump tank is removed through line 12 for further processing. The oil-poor water from the clarifier tank, the scavenge zone, the separator, and the dross from the clarifier tank, which together make up the effluent stream, are deposited in the sand separator zone 23, for example by simple gravity settling. It is then processed. The sand is removed and discarded by line 13;
The flow of treated water is taken off by line 14 to a coagulation zone 24. In flocculation zone 24, a substantial amount of the clay suspended in the treated water is solidified and the solidified clay slurry and treated water are removed in line 15 to centrifuge zone 25. In the centrifuge zone, the solidified clay is separated from the process water and is disposed of via line 16. The water, which has a substantially reduced clay and sand content compared to the effluent effluent, is recovered from the centrifuge zone and recycled by line 17 to be mixed with fresh water and fed into the hot water process. Ru. As previously mentioned, coagulants are made from wheat, corn or potato starch, which have been hydrolyzed. Hydrolysis is accomplished simply by heating the starch in the form of an aqueous suspension to about 85° to 95°C, preferably about 90°C. Starch is preferably 100% water
It should be present in an amount of 1 to 5 g, preferably 2 to 3 g per ml. In order to control the size of the starch particles and prevent their swelling, it is essential that the hydrolysis be carried out in the presence of certain selected salts, which act as electrolytes and keep the size of the particles within the desired dimensions. was discovered. Among the salts that can be used for this purpose are sodium, potassium, ammonium, magnesium,
There are salts of metals such as calcium and aluminum. Each anion is a sulfate group, an acetate group,
It can be a hydrochloric acid radical, a nitrate radical, a chloric acid radical, a hydrobromic acid radical, a hydroiodic acid radical, a thiocyanic acid radical, a phosphoric acid radical, etc. As applied to tar sand ponds,
Particularly useful for the purposes of the present invention is _CaAlPO4 wheat starch. Of course other salts such as AlPO ₄ , NaAlPO ₄ etc. may also be used. Although the salts may be added in any desired form, it has been found to be preferable to form the salts in situ, especially when the salts are generally insoluble in water. Thus, for example, the preferred _CaAlPO4 salt is conveniently formed in situ by adding specified amounts of calcium hydroxide, aluminum sulfate, sodium phosphate into an aqueous wheat starch hydrolysis medium. . The salt produced in any case is starch
Approximately 10 to 30 g per 100 g of starch, preferably 15 to 20 g per 100 g of starch. In the case of treatment of known phosphate mineral muds from phosphate mining operations with the flocculants of the present invention, the presence or addition of phosphates such as sodium phosphate is unnecessary;
May be omitted from salt production. According to the invention, alcohols, preferably 1
When lower aliphatic alcohols such as methanol, ethanol, and propanol with ~5 carbon atoms are added to the hydrolyzate, the particle size and effectiveness of the resulting flocculant material is enhanced, making the method superior to other known It has also been discovered that the results are further improved over flocculants. Alcohol can be added to the starch hydrolyzate in one of two ways. (1) By simultaneous direct addition of alcohol and hydrolyzate to Kass pond water. (2) By addition of alcohol to the hydrolyzate itself before using it in the kasu pond. In the latter case the alcohol is usually added to the hydrolyzate in excess of what is actually needed, so overnight settling of the flocculant allows the excess alcohol to be recovered by distillation etc. and then recycled. , which offers some obvious economies. Alcohol should be added in an amount of at least 1/10 to 1/5 volume of the hydrolyzate. Alternatively, but less preferably, acetone instead of alcohol,
Other additives such as yeast or lactic acid can be used. If desired, the resulting alcohol-treated hydrolyzate can then be further processed by drying (i.e., freeze drying, air drying, spin drying, etc.) to essentially remove all the water. The present invention provides a powder that is convenient for handling, storage and transportation, but can be easily redispersed in water at the processing site. Yet another aspect of the invention was found in its application to bituminous tar sands. The results obtained with salt and alcohol treated starch hydrolyzate were 454.6 with powdered cement as flocculant and containing 20% solids.
(100 gallons) of sludge at least about
This can be further enhanced by introducing the standard in the form of a dilute slurry of 1.36 kg (approximately 3 lbs.).
The effect of adding powdered cement to the flocculant is to provide a rapidly settling sludge layer with improved shear strength and permeability properties. According to this aspect of the invention, the wheat starch flocculant and cement are preferably mixed with the effluent stream as separate or combined slurries. The amount of cement injected is at least 3.0 pounds of cement per 100 gallons of flange, and preferably 1.633 pounds of cement per 100 gallons of flange.
(3.6 lbs. or more)], and this sludge is expected to accumulate when the liquid fraction of the tar sands stream is discharged into ponds and allowed to settle. The concentration of starch flocculant injected typically ranges from 0.1 to 0.2 pounds per 100 gallons of sludge. Initial treatment of existing ponds involves dispersing the required amount of cement and/or starch flocculant over the surface of the pond (or distributing the recycle stream) to achieve a cement concentration of at least 3 pounds per 100 gallons of sludge. by other means such as recirculation by injection into the
would require. For the sole purpose of defining the required cement and starch flocculant concentrations, "sludge" is more specifically defined as a "standardized" sludge containing approximately 20% weight/volume solids. As noted earlier, in an actual settling pond, the division between the clarified water layer and the sludge layer is not clear and changes easily, and the properties of the sludge layer change from the top to the bottom. In order to determine the minimum dosage of starch flocculant and starch flocculant, it is necessary to calculate the "average standardized" sludge from the samples taken from the pond. Water from the clarified aquarium is drawn off by a pump to be mixed with fresh water and fed into the hot water process. The following examples are provided for illustrative purposes and do not limit the scope of the invention for the preparation and use of starch flocculants. Synthesis of Hydrolyzed Wheat Starch Flocculant 5 g of primary wheat starch [Supergel 1201 - International, Glen Products, Limited
Grain Products Ltd., Canada)] was weighed into a flask fitted with a reflux device. _CaAlPO4
200 ml of an aqueous solution containing .
0.617g of _CaAlPO4 in the presence of starch in aqueous solution
of Al ₂ (SO ₄ ) ₃・18H ₂ O, 0.704 g of Na ₃ PO ₄・
Formed in situ by addition of 12H ₂ O and 0.436 g Ca(OH) ₂ . The suspension was kept at 90℃±5 for 2 hours while stirring at the same time.
Refluxed at °C. Hydrolysis was considered complete when the undissolved starch was converted to a colloidal solution. The volume was then adjusted to 250 ml with distilled water, thus giving a raw solution of 20000 ppm CaAlPO ₄ wheat starch. Example 1 A series of tubes containing 50 ml of tar sands sludge with a solids content of 10% were mixed with 0.5 ml of the above-mentioned
CaAlPO ₄ was treated with wheat starch and, in the cases indicated in the table below, with alcohol or yeast. The sludge contained 0.25% bityumen. Half of the tube was centrifuged and the results are shown in the table below. The other half of the tubes are left to settle on their own and the results are also reported in the table.

[Table] From the above data, the solids content was better than the control sample when the sludge was treated with both wheat and additives and centrifuged, and clearly superior when the sludge was allowed to settle on its own. It is clear that A comparative series of experiments was conducted using polyacrylamide as the flocculant. The results are shown in Table 2 below.

Table: When wheat starch hydrolyzed under the same conditions was used, a clear supernatant free of solids was obtained, thus proving the superiority of the wheat starch of the invention over the polyacrylamide of the prior art. are doing. Example 2 Ethyl alcohol (50 ml) was added to 250 ml of the hydrolyzed CaAlPO ₄ wheat starch from Example 1 and the mixture was left overnight. Substantially all excess alcohol is then removed from the mixture in a Soxhlet extractor.
It was removed by heating at 80° C. for 20 minutes and the residue was dried in an oven. After redispersing 2% starch in water, two 50 ml samples of the sludge with an initial solids content of 12% were taken. One was used as a control. Hydrolyzed redispersed in the second sample
Added 0.5 ml of _CaAlPO4 wheat starch (200 ppm). After centrifuging the two samples for 320 minutes, the following results were observed. Control……12%, weight/weight (w/w)……
The supernatant liquid is not clear (1.4% solids). CaAlPO ₄ starch……28.1% weight/weight……
...The supernatant liquid is clear (no solids). Example 3 Phosphate slime (Swift, Silver, City, FL) having a solids content of 2.66% (w/w) and a pH of 6.34 was treated with the hydrolyzed starch of Example 1. Two commercially available polyacrylamide flocculants (Magnifloc 573C and 1820A, American, Cyanamid, Company) were also used for comparison purposes. The results of these experiments are shown in Table 3 below.

[Table] The supernatant was clear for all samples, both treated and untreated. It will be seen from the above results that starch was clearly superior in terms of the amount of solids settled. The importance of viscosity is that a low viscosity for the untreated sample indicates that the solids are essentially dispersed, whereas a much higher viscosity for the polyacrylamide sample indicates that the solids are agglomerated and thus The viscosity of the sample flocculated by the wheat means that settling is not significantly retarded, while at the same time it overloads the settled mass with sand. It is best understood when you realize that it allows you to load. The main ingredients of phosphate slime are: Carbonate-fluoroapatite, quartz,
Synthesis of montmorillonite and attapulgiaite, hydrolyzed corn and potato starch flocculants To prepare the hydrolyzed starch, a mixture of starch and an aqueous solution containing the required amount of salt was prepared as above for wheat starch. A 20000 ppm raw material solution was prepared by refluxing in the same manner.
Hydrolysis was considered complete when the insoluble starch was converted to a colloidal solution. A summary of the starch flocculants prepared is given in Table 4 below.

【table】

Table: To test the effectiveness of the synthesized starch flocculant, two sludge suspensions containing 5.5 and 17.3% solids by weight, respectively, were used. Additionally, a synthetic polyacrylamide flocculant was used for comparison purposes. The test criteria used were refiltration rate), autosedimentation, and sedimentation by centrifugation for 30 minutes at a relative centrifugal force of 790 g at the bottom of the tube. The results of the refiltration tests and the preliminary tests on self-sedimentation were superior to those made from potato starch, so Table 5 shows the centrifugal sedimentation studies performed with potato starch flocculants. only.

Table 5 It is clear from the data presented in Table 5 that starch flocculants are decisively superior to polyacrylamide flocculants in terms of the quality of the supernatant produced. In experiments where starch flocculant was used at a sludge concentration of 17.3 weight percent, the supernatant had a solids content of up to 2.4 weight percent for those in which no flocculant was used. There were no cloudy solids. Among starch flocculants, starch containing AlPO ₄ appears to be the best. Additionally, starch flocculants are equally effective on sludges from which no oil has been removed, such as during processing of oil-removed sludges, while polyacrylamide flocculants are more effective than sludge suspensions from which no oil has been removed. It has also been found that oil-free products are more effective.

[Brief explanation of the drawing]

The drawing is a schematic representation of the hot water extraction method. 1 to 17: Line (pipe), 18: Conditioning drum or crusher, 19: Preparation water reservoir, 20: Separation zone,
21: Sweeping zone, 22: Foam settling tank, 23: Sand separation zone, 24: Coagulation zone, 25: Centrifugal separation zone.

Claims (1)

[Scope of Claims] 1. A colloidal sludge suspension containing clay minerals or metal oxide-hydroxides is treated with a flocculant to substantially separate the water from the suspended solids. In the method of destabilizing the flocculant, the flocculant is made of hydrolyzed wheat, corn or potato starch obtained by aqueous hydrolysis of starch in the presence of insoluble metal salts formed in situ. A method of characterizing something. 2. The method of claim 1 in which the sludge suspension is derived from a bituminous tar sands mining operation. 3. The method of claim 1, wherein the sludge suspension is a phosphate slime obtained from a phosphate mining operation. 4. The method of claim 1, wherein the hydrolyzed starch is calcium aluminum phosphate wheat starch. 5. The method of claim 1, wherein the hydrolyzed starch is AlPO ₄ potato starch. 6. The method of claim 1, wherein the hydrolyzed starch is further treated with additives consisting of lower aliphatic alcohols, acetone, yeast or lactic acid prior to application to the sludge suspension. 7. The method of claim 6, wherein said additive is an excess of alcohol, and wherein said excess alcohol is recovered and recycled for further treatment of the hydrolyzed starch. 8. The method of claim 6, wherein the additive treated hydrolyzed starch is dried to a water redispersible solid. 9. The method of claim 1, wherein the sludge suspension is simultaneously treated with hydrolyzed wheat starch and an additive consisting of a lower aliphatic alcohol, acetone, yeast or lactic acid. 10. The method of claim 1, wherein the concentration of flocculant in the sludge suspension is controlled to provide at least 50 parts per million (50 ppm). 11. The method of claim 1, wherein cement is added to the sludge suspension. 12 Bituminous tar sands sludge with a solid content of 20% in which the amount of cement added is 454.59
11. The method of claim 11, wherein: at least 3 pounds (1.3608 kilograms) per 100 imperial gallons. 13. A flocculant composition comprising hydrolyzed wheat, corn, or potato starch obtained by aqueous hydrolysis of starch in the presence of an insoluble metal salt formed in situ. 14. The composition of claim 13, wherein the starch is wheat starch and the salt is a salt containing calcium, aluminum and phosphate ions. 15 Claim 1 in which the starch is potato starch and the salt is AlPO ₄ made on the spot.
Composition of item 3. 16. Flocculant compositions comprising hydrolyzed starch obtained by aqueous hydrolysis of wheat starch in the presence of metal salts formed in situ, and additives consisting of lower aliphatic alcohols, acetone, yeast, or lactic acid. . 17. The composition of claim 16, wherein the starch is wheat starch and the salt is a salt containing calcium, aluminum and phosphate ions. 18. The composition of claim 16, wherein the aqueous hydrolyzed starch is dried to form a water redispersible solid.