Compositions and methods for increasing the production of aluminum hydroxide in an aluminum hydroxide production process

Description

Field of the Invention

[0001] The present invention, relates to compositions and methods used as crystal growth modifiers (CGM) in Bayer process. The CGM compositions comprise a component of crude corn oil derived from a bioethanol production process and / or a component of biodiesel. The CGM compositions may be used to modify particle size and distribution of precipitated alumina trihydrate in a precipitation liquor crystallization process.Background of the Invention

[0002] Aluminum is the world's most widely used non-ferrous metal. Although it is one of the most abundant elements, aluminum in its pure state is rare. Instead aluminum is primarily converted from aluminum oxide (Al 2 O 3 ), which is also known as "Alumina". Aluminium oxide is largely produced or extracted from aluminum ores, especially from Bauxite. Aluminum ores contain other materials, such as silica, various iron oxides, and titanium dioxide, which need to be separated from the alumina. After the aluminum oxide is separated from those other materials, it can be refined to produce aluminum metal. Separating aluminum from those other materials is the largest single cost associated with aluminum metal production.

[0003] Aluminum is typically separated from other materials in ore by the Bayer process. The Bayer process comprises a number of sequential stages: digestion, clarification, precipitation, classification, and calcination. In the digestion stage, alumina is extracted by digesting the bauxite ore in a solution of sodium hydroxide under high pressure and temperature. This forms soluble sodium aluminate. In the clarification stage, solid phase residue, known as "red mud", is removed from the sodium aluminate in solution. In the precipitation stage, aluminum hydroxide (Al(OH) 3 ) crystals are precipitated from the sodium aluminate solution. The growth of these crystals is aided by the use of fine aluminum hydroxide particles known as "seeds". These seeds provide anchor surfaces on which the crystals nucleate and grow. In the classification stage, the crystals and seeds are separated from the process liquor. Finally in the calcination stage the aluminium hydroxide decomposes to aluminium oxide, the alumina end product.

[0004] Careful control over the crystal size formed during the precipitation stage, results in increasing the overall yield of aluminum hydroxide. As a result, operators carefully control operating parameters, such as precipitation temperature and cooling rate. Certain crystal sizes are ideal for easy and efficient separation from the liquor and further processing. Other crystal sizes are ideal for use as future seeds.

[0005] WO2011 / 002952 A2 relates to ways to increase the output of a high quality product from the precipitation liquor crystallization process exemplified through the aluminum hydroxide recovery processes such as the Bayer process. Disclosed is a method of increasing the size of precipitated of a liquor. One embodiment relates to the use of a crystal growth modifier compositions added to the precipitation process to increase the particle size distribution of the precipitated alumina trihydrate.

[0006] Extensive efforts have been invested into finding chemical additives and methods to control the crystal sizes produced during precipitation. Such efforts include adding crystal growth modifiers (CGM) in the precipitation stage. Nevertheless, there is still a desire for improvements and enhancements for the aluminium hydroxide production process to address production quality and economic concerns.Brief Summary of the Invention

[0007] To satisfy continued industry needs, compositions and methods relating to the modification of the crystallization of aluminum hydroxide in an aluminum hydroxide production process, such as the Bayer process, have been developed. The present invention relates to a composition for enhancing the production of aluminium hydroxide crystal agglomerates from a precipitation liquor crystallization process with the features according to claim 1.

[0008] The present invention also relates to a method for enhancing the production and recovering of aluminium hydroxide crystal agglomerates from a precipitation liquor crystallization process with the features according to claim 2.

[0009] Preferred embodiments are outlined in the dependent claims.Detailed Description of the Invention

[0010] The following are definitions that apply to the relevant terms as used throughout this specification.

[0011] "A / C " means the alumina to caustic ratio.

[0012] "CGM" means crystal growth modifier.

[0013] "Biodiesel" means the mono alkyl esters of long chain fatty acids derived from vegetable oils or animal fats.

[0014] "Hydrocyclone" means a device used to classify, separate, or sort particles in a liquid suspension based on the ratio of their centripetal force to fluid resistance. Hydrocyclones are typically used to separate dense and coarse particles from light and fine particles. Hydrocyclones often have a cylindrical section at the top where liquid is being fed tangentially and a conical base. Hydrocyclones often have two exits on the axis: a smaller one at the bottom (for underflow) and a larger one at the top (for overflow). Generally the underflow is the denser or coarser fraction, while the overflow is the lighter or finer fraction.

[0015] "Weight Percent Ratio" means the total weight fraction of one reagent within 100 grams of the composition or mixture.

[0016] "Product yield" means the amount of aluminum hydroxide solid content within the precipitating vessel at the end of a precipitation run. An increased product yield is generally indicated by a lower liquor aluminum hydroxide concentration for the corresponding vessel.

[0017] "Liquor" or "Bayer Liquor" means a caustic, liquid medium that has run through at least a portion of a Bayer process in an industrial facility.

[0018] "Precipitation Liquor" means aluminate containing liquor present in an aluminum hydroxide precipitation step of an alumina production process. The aluminate liquor may be referred to by various terms known to those of ordinary skill in the art, for example: "pregnant liquor", "green liquor", and "aluminum hydroxide precipitation feed".

[0019] "Precipitation Feed Liquor" means the precipitation liquor that flows into a precipitator of an aluminum hydroxide precipitation process.

[0020] "Thickener" or "Settler" means a vessel used to effect a solid-liquid separation of a slurry, often with the addition of flocculants. The vessel may be constructed and arranged to receive a slurry, retain the slurry for a period of time sufficient to allow solid portions of the slurry to settle downward (underflow) away from a more liquid portion of the slurry (overflow), decant the overflow, and remove the underflow. Thickener underflow and thickener overflow are often passed on to filters to further separate solids from liquids.

[0021] "Spent Liquor" refers to liquor resulting from the removal of precipitated aluminum after the final classification stage. It is often returned back to the digestion of the Bayer process.

[0022] "Bioethanol Process" means a process for the production of ethanol or ethyl alcohol from starch or sugar-based feedstocks by either wet milling or dry milling.

[0023] "Wet Milling Process" means a process used in a Bioethanol Process for processing corn into ethanol. In a wet milling process, corn kernels or grains are conditioned into slurry in warm water and dilute acid. As slurry, the proteins break down and starch is released. The slurry is processed (milled) through a series of grinders to separate the corn germ and fiber from the starch. Crude corn oil is extracted from the germ as a byproduct. Ethanol production makes use of the starch. The remaining protein, fat, fiber and other nutrients can be returned to the global livestock and poultry feed markets or used for other known purposes.

[0024] In the event that the above definitions or a description stated elsewhere in this application is inconsistent with a meaning (explicit or implicit) which is commonly used, or in a dictionary, the application and the claim terms in particular are understood to be construed according to the definition or description in this application, and not according to the common definition, or dictionary definition. In light of the above, in the event that a term can only be understood if it is construed by a dictionary, if the term is defined by the Kirk-Othmer Encyclopedia of Chemical Technology, 5th Edition, (2005), (Published by Wiley, John & Sons, Inc.), this definition shall control how the term is to be defined in the claims.

[0025] At least one embodiment of the invention is directed toward a composition for enhancing the production of aluminium hydroxide crystal agglomerates from a precipitation liquor crystallization process, characterized in that the composition consists essentially of: a crude corn oil component, wherein the crude corn oil component comprises 1-10 percent by weight C16 and C18 ethyl esters, 50-95 percent by weight diglycerol esters and triglycerol esters of long chain fatty acids; and a carrier liquid, the carrier liquid comprising a hydrocarbon liquid, wherein the hydrocarbon liquid is a hydrocarbon oil comprising aliphatic or aromatic oil compounds chosen from the group consisting of paraffinic oils, naphthenic oils, mixed paraffinic and aromatic oils, the residue of C10 alcohol distillation, and mixtures thereof.Crude corn oil component

[0026] The crude corn oil component comprises, and in some embodiments consists essentially of, a distinct phase produced during a corn-based bioethanol process. In a corn-based bioethanol process, corn is converted into ethanol. In at least one embodiment, the bioethanol process utilizes wet milling.

[0027] The crude corn oil comprises mono alkyl esters, diglycerol esters and triglycerol esters of long chain fatty acids, free fatty acids and other components. The mono alkyl fatty acid esters comprise C 16 -C 18 ethyl esters having the following formula:

[0028] In some embodiments, R is C15-C17 (corresponding to C 16 -C 18 ethyl esters). In some embodiments, the fatty acid chains of the C 16 -C 18 ethyl esters can include saturated fatty acid chains and can include unsaturated fatty acid chains. In some embodiments, the fatty acid chains of the C 16 -C 18 ethyl esters are unbranched.

[0029] Examples of suitable crude corn oil components include crude corn oil byproduct having at least 1 wt % C 16 -C 18 ethyl esters; 1.5 - 10 wt % C 16 -C 18 ethyl esters; and 1.5 - 8 wt % C 16 -C 18 ethyl esters. Examples of suitable crude corn oil derived from or that is a byproduct of a corn based bioethanol process can include the following components: major components, including C16:0 ethyl ester, C16:0 acid, C18:2 ethyl ester, C18:2 acid; C18:1 ethyl ester, C18:1 acid; C18:0 ethyl ester, C18:0 acid; fatty acid monoglycerol ester (MG); fatty acid diglycerol ester (DG); fatty acid triglycerol ester (TG); and some sterols, for example, stigmasterol, sitosterol, methyl cholesterol; minor components, including tocopherol, squalene, C16:1 ethyl ester, C16:1 acid, C14:0 ethyl ester, C14:0 acid; and further minor components can include C12:0 acid, C10:0 acid, myo-inositol, C4:0 acid, C5:0 acid, 1,3-butanediol, 1,3-propanediol, butanedioic acid, etc.

[0030] Representative examples of the constituent parts of suitable crude corn oil byproduct samples are listed on Table I. Table I lists the constituents of commercially available crude corn oil byproduct samples which were evaluated by Gas Chromatography - Mass Spectrometry (GC-MS) and were quantified by high temperature Gas Chromatography - Flame Ionization (GC-FID) with C21:0 acid as internal standard. Table I: Components Sample Ethyl ester Fatty acid Fatty acid monoglycerol ester Sterol Fatty acid diglycerol ester Fatty acid triglycerol ester other Sum 12.63%12.43%0.84%1.08%5.62%77.06%0.36%100.00 %22.13%12.81%0.53%0.64%6.08%77.80%0.00%100.00 %31.92%10.59%0.77%0.29%0.31%86.12%0.00%100.00 %47.66%4.03%0.71%0.40%3.43%83.77%0.00%100.00 %51.91%10.65%0.70%0.20%2.11%84.42%0.00%100.00 %63.17%10.10%0.69%0.40%3.37%82.28%0.00%100.00 %75.59%8.92%0.90%0.81%4.41%79.37%0.00%100.00 %Each Sample (1-7) is taken from distinct amounts of commercially available crude corn oil byproduct acquired from differing bioethanol suppliers in the United States of America.

[0031] According to the invention, the crude corn oil component comprises 1-10 percent by weight C16 and C18 ethyl esters, 50-95 percent by weight diglycerol esters and triglycerol esters of long chain fatty acids.Biodiesel Component

[0032] The biodiesel component comprises, and in some embodiments consists essentially of, biodiesel or mixtures of biodiesels. The biodiesel(s) comprises mono alkyl esters of long chain fatty acids and may comprise free fatty acids. Examples of suitable biodiesels and their compositional components include, but are not limited to, one, some, or all, of those listed on Table II: Table II Biodiesel Composition Examples Components (wt %) (all methyl esters) Oil or fat type C8:0 C10:0 C12:0 C14:0 C16:0 C18:0 C20:0 C22:0 C24:0 C18:1 C22:1 C18:2 C18:3 SUM Soybean0000.110.34.700022.5054.18.3100Rapeseed00002.72.800021.950.913.18.6100Beef-tallow00.10.13.325.219.200048.902.70.5100Peanut000010.48.900047.10.232.90.5100Canola0000.13.93.100060.20.521.111.1100Olive0000113.600075.309.50.6100Coconut8.3646.718.39.22.90006.901.70100Corn00009.93.100029.1056.81.1100Palm0.10.10.91.343.94.90003909.50.3100Safflower0000.16.63.300014.4075.50.1100Sunflower0000.165.900016071.40.6100Sunola000034.400088.204.30.1100Butterfat5.533.611.633.411.400027.803.10.6100Lard00.10.11.425.515.800047.108.91.1100Cottonseed0000.822.93.100018.5054.20.5100Crambe00002.070.72.090.81.1218.8658.5196.85100Linseed00004.922.4100019.7018.0354.94100H.O. safflower0000.345.461.750.230079.36012.860100Sesame000013.13.9200052.84030.140100Further details of the biodiesels, biodiesel components and methyl esters from biodiesel is found in Sanford, S.D., et al., "Feedstock and Biodiesel Characteristics Report," Renewable Energy.

[0033] The mono alkyl esters of long chain fatty acids of the biodiesel(s) comprise methyl esters. The methyl esters can have the following formula: In some embodiments, R is C 7 -C 21 (corresponding to C 8 -C 22 methyl esters). In some embodiments, R is C 15 , C 17 or C 21 (corresponding to C 16 , C 18 or C 22 methyl esters). In at least one embodiment C 8 -C 22 methyl esters make up between 80-98 weight percent of the total number of methyl esters present. In some embodiments, the fatty acid chains of methyl esters include saturated fatty acid chains. In some embodiments, the fatty acid chains of methyl esters include unsaturated fatty acid chains. In some embodiments, the fatty acid chains of the methyl esters are unbranched.

[0034] In at least one embodiment, the mono alkyl esters of long chain fatty acids are methyl esters and comprise up to 98 wt% or more of the biodiesel component. The free fatty acids may constitute up to 0-2 wt% or more of the biodiesel component.

[0035] In at least one embodiment, the biodiesel component comprises, and can consist essentially of, a soybean based biodiesel, a rapeseed based biodiesel, or mixtures thereof.Carrier Liquid

[0036] According to the invention, the composition comprises a carrier liquid. The carrier liquid comprising a hydrocarbon liquid, wherein the hydrocarbon liquid is a hydrocarbon oil comprising aliphatic or aromatic oil compounds chosen from the group consisting of paraffinic oils, naphthenic oils, mixed paraffinic and aromatic oils, the residue of C10 alcohol distillation, and mixtures thereof.

[0037] In at least one embodiment, the hydrophobic liquid is an alcohol distillation residue. An alcohol distillation residue is a fatty alcohol-ether-ester complex derived from an alcohol distillation process. These residues form as bottoms or residual waste materials remaining from the production of aliphatic or alkyl alcohols, for example a C 10 - C 22 alcohol. An example of suitable waste material is the C 19 alcohol distillation residue having a boiling point of about 250 °C. (482 °F.). It has a specific gravity of about 0.862, OH-number about 90, weight percent acetic groups about 0.07, and weight percent carbonyl groups about 0.5. Chemically, it is 57-73 weight percent of primary branched chain C 10 - C 22 alcohols and 29-41 weight percent of mixed long chain esters and ethers (C 18 - C 33 ester; C 18 -C 22 ether).

[0038] In at least one embodiment, the oil carrier is a mixture of a tall oil fatty acid mixed with C 10 alcohol distillation residue, naphthenic oil, and any combination thereof. The weight proportions of this mixture are within the range of 12:88 to 20:80, preferably 15:85. It may be dosed in an amount of between 15-25mg / l preferably at 20 mg / l.Fatty Acid Component

[0039] In at least one embodiment, the fatty acid component comprises, and in some embodiments consists essentially of, a fatty acid or a blend of fatty acids having an alkyl chain length of C 8 -C 10 carbon atoms. In some embodiments, the C 8 -C 10 fatty acid includes a carbon backbone which is free of functional groups, is saturated and unbranched.

[0040] Some examples of suitable fatty acids and blends thereof are described in US Patent No. 7,955,589. One example is a C 8 -C 10 fatty acid composition having an average molecular weight of 154 g / mol. The composition's distribution of fatty acid chain lengths are: C 6 < 6%, C 8 53-60%, C 10 34-42% and C 12 < 2%. The carbon chain(s) may be saturated or unsaturated, branched or unbranched, and is free of functional groups. Representative examples of this composition include the commercially available product C-810 available from Proctor and Gamble which may be dispersed in commercially available paraffinic hydrocarbon oil sold under the name ESCAID 110 from ExxonMobil.

[0041] The C 8 -C 10 fatty acid can be dissolved in the carrier liquid (described below). An example includes a hydrocarbon oil that has a boiling point above about 90 °C (about 200 °F). In some embodiments, the ratio of the C 8 -C 10 fatty acid and the hydrocarbon oil can have a weight proportion within the range of 12:88 to 20:80, preferably 15:85.CGM Formulation

[0042] In at least one embodiment, the CGM compositions comprise or essentially consist of the crude corn oil component, the biodiesel component or mixtures thereof. In some embodiments, the compositions can further include the carrier liquid. In some embodiments, the CGM compositions comprise, and in some embodiments essentially consist of, 1) the crude corn oil component, the biodiesel component or mixtures thereof; 2) the carrier liquid; and 3) the fatty acid component. In variations of the embodiments herein, the CGM compositions can be free of added water.

[0043] When the CGM comprises the crude corn oil component, in some embodiments the crude corn oil component comprises 1-100 wt % of the CGM. In various embodiments, the CGM comprises the crude corn oil component in the following amounts: 10-100 wt %; 40-100 wt %; 70-100 wt % and 98-100 wt %. In some embodiments, when the CGM comprises the crude corn oil component, the C 16 -C 18 ethyl esters can be 0.01 - 10 wt % of the CGM and the diglycerol and triglycerol esters can be 0.5-95 wt% of the CGM. In some embodiments, the C 16 -C 18 ethyl esters and the diglycerol and triglycerol esters can be 25 wt% or more, 50 wt% or more, or 85 wt% or more of the CGM. Embodiments of the invention can include CGM compositions having variations of the above amounts of the crude corn oil component having variations of the above crude corn oil compositions.

[0044] When the CGM comprises the biodiesel component, biodiesel component may comprise 1.0-100 wt % of the CGM. In various embodiments, the CGM comprises the biodiesel component in the following amounts: 10-100 wt %; 40-100 wt %; 70-100 wt % and 98-100 wt %. Embodiments of the invention can include CGM compositions having variations of the above amounts of the biodiesel component having variations of the above biodiesel compositions.

[0045] In at least one embodiment, the CGM comprises a mixture of the crude corn oil component and the biodiesel component. The present disclosure includes any mixture of the two components in any ratio. Examples of CGM comprising the biodiesel component and the crude corn oil component include, but are not limited to, CGM having mixtures ratios of 1-99:1-99, 10-90:10-90, 50:50, 25:75, and 75:25.

[0046] In at least one embodiment, the CGM comprises or consists essentially of the crude corn oil component, the biodiesel component or mixtures thereof. In at least one embodiment, the CGM is used in a neat form. In at least one embodiment, the CGM formulation comprises dissolving the crude corn oil component and / or the biodiesel component in the carrier liquid. The carrier liquid may make up 35-85 weight percent of the CGM formulation. The present disclosure includes any mixture of the crude corn oil component, the biodiesel component, and the carrier liquid in any ratio.Application of CGM Compositions

[0047] In at least one embodiment, the mixed / blended CGM composition is delivered into the green or pregnant liquor of the precipitation process of an on-going Bayer process. The blended CGM compositions can be introduced into the process in an amount effective to obtain the changes desired. In some embodiments, the compositions can be introduced in their primary form without any further preparation.

[0048] The precipitation process in the Bayer process involves nucleation, initial crystal growth, and agglomeration of those crystals into a coarse or sand-like alumina trihydrate particles. The coarse or sand-like alumina trihydrate particles are dried, and often calcined, to obtain Al 2 O 3 as the commercial end-product of value.

[0049] The green or pregnant liquor present in the precipitation portion of the Bayer process is a hot caustic solution obtained after elimination of the red mud. This green liquor contains dissolved sodium aluminate. Some of the dissolved sodium aluminate particles are fine particle material (e.g. -325 mesh or smaller). The green liquor, and optionally additional fine particle alumina trihydrate, is introduced into a suitable precipitating tank or a series of connecting tanks. Here, the green liquor is cooled under agitation causing precipitation of alumina hydrate crystals on the seeds. While some large crystal growth is desired, complete elimination of the fine particle material is often not the most desired outcome. This is because some remaining fine particle material may be reused as seeds for future precipitation steps.

[0050] In at least one embodiment, the CGM composition is introduced into the precipitation liquor via one or more routes. As examples, the crystal growth modifier may be added, via in-line injection, to the precipitation liquor at the following steps of a Bayer process: a) to a precipitation feed liquor, b) to a seed slurry or other input stream to a precipitation tank, c) directly into a precipitation tank, and d) a combination thereof. In some embodiments, the CGM composition is added in such a manner as to be homogeneously distributed in the Bayer precipitation environment for unimpeded contact with the fine particulate. In at least one embodiment, the CGM is emulsified prior to its addition to the precipitation liquor.

[0051] In at least one embodiment, the amount of the CGM introduced to the precipitation liquor is proportional to the surface area of the available aluminum hydroxide seed. For example the CGM may be added in a range of: from about 0.01 to about 30 mg of CGM / m 2< of the available aluminum hydroxide seed surface area. In some embodiments, the amount can range from about 0.1 to about 15 mg of CGM / m 2< of the available aluminum hydroxide seed surface area. In some further embodiments, the amount can be less than about 8 mg of CGM / m 2< of the available aluminum hydroxide seed surface area is used. In some embodiments, the amount can be 1-3 mg of CGM / m 2< of the available aluminum hydroxide seed surface area.

[0052] In at least one embodiment, the dosage of CGM added is relative to the volume of liquor it is added to. This is of particular value in circumstances where the available aluminum hydroxide surface area cannot be reliably determined. The amount of CGM added may range from about 0.01 to about 400 mg of CGM / liter of precipitation liquor. In at least one embodiment, the amount ranges from about 0.05 to about 200 mg of CGM / liter of precipitation liquor. In at least one embodiment, the amount may be less than about 100 mg of CGM / liter of precipitation liquor. In at least one embodiment, the amount may range from about 10 to about 40 mg of CGM / liter of precipitation liquor.

[0053] Representative examples of methods of introducing the CGM formulation into the Bayer process include one or more of the methods described in US Patents: 8,784,509, 7,771,681, 7,976,820, 7,976,821, 7,955,589, 4,737,352 and US Published Patent Applications 2007 / 0172405 and 2014 / 0271416. The CGM formulation, may be used in combination with one or more of other efforts related to modification of crystallization of aluminum hydroxide in alumina production processes such as those described in: US Patent 5,106,599; EP0465055B1; US Patent 6,599,489; US Patent 5,312,603; and US Patent 6,168,767.

[0054] Applications and uses for the produced alumina include, but are not limited to, using in the alumina in the production of aluminium metal, abrasives, fillers in plastics and catalyst support for industrial catalysts.

[0055] Each of the components and methods disclosed herein can be used separately, or in conjunction with other components and methods, to provide improved compositions and methods for making and using the same. Therefore, combinations of components and methods disclosed herein may not be necessary to practice the disclosure in its broadest sense and are instead disclosed merely to particularly describe various embodiments.Examples

[0056] The foregoing may be better understood by reference to the following examples, which are presented for purposes of illustration and are not intended to limit the scope of the invention. In particular the examples demonstrate representative examples of principles innate to the invention. These principles are not strictly limited to the specific condition recited in these examples. As a result, it should be understood that the invention encompasses various changes and modifications to the examples described herein.

[0057] For purposes of illustration, a precipitation test was conducted on CGM compositions (Example 1 and Example 2) made in accordance with some embodiments of the invention. These CGM compositions were compared to various other crystal growth modifiers and controls. The tests were run using fresh pregnant liquor obtained from the reconstitution of plant spent liquor.Precipitation Test Procedure:

[0058] Tests were run using either fresh pregnant liquor obtained from an alumina plant or using reconstituted pregnant liquor prepared by adding alumina trihydrate the plant spent liquor. The precipitation tests were performed in 250-mL Nalgene ®< bottles rotated end-over-end, at approximately 10-15 rpm, in an Intronics temperature-controlled water bath. Approximately 200 mL of liquor was accurately weighed into a series of bottles. The additive, where required, was dosed to the appropriate bottles and all the bottles were then placed in the rotating bath for equilibration at the given test temperature (about 145°F to about 160°F). After equilibration, the bottles were removed, quickly charged with the required quantity of seed and immediately returned to the water bath. The bottles were rotated for the given test duration, typically for four to six hours.

[0059] On completion of the test, the bottles were removed from the bath. 10 mL of a sodium gluconate solution (400 g / L) was added to the remaining slurry and mixed well to prevent any further precipitation. The solids were collected by vacuum filtration and were thoroughly washed with hot deionized water and dried at 110 °C.

[0060] The particle size distribution and specific surface area were determined on a Malvern Particle Sizer. Results are illustrated in Tables III and IV below. The particle size distribution is presented by three quantiles, d(0.1), d(0.5) and d(0.9). These represent the diameters under which fall 10%, 50% and 90% of particles by volume, respectively. The percent increase over the control quantile particle size is the difference between the additive dosed and control for the respective quantile particle size divided by the control quantile particle size. The effect of CGM on the particle size distribution is inferred from the increase of the percent of particles sized greater than 45 µm (the size of alumina trihydrate product commonly monitored across the industry) in the precipitation product relative to an undosed control sample. The greater the increase, the better the CGM performed in producing the large size crystals.Testing Samples and Sample Tests

[0061] Two samples of Example 1 and two samples from Example 2 were separately compared against a two control samples (no crystal growth modifiers) and two samples of each of commercial products N7837 and N85651 using the precipitation test procedure as described above. The test results are described and shown in Tables III and IV below. The testing sample formulations were as follows: The sample labeled "Example 1" was a biodiesel formula in accordance with an embodiment of the invention comprising 20% biodiesel and 80% hydrocarbon oil, wherein the biodiesel was soybean oil based methyl ester.

[0062] The sample labeled "Example 2" was a crude corn oil formula in accordance with an embodiment of the invention comprising 40% crude corn oil derived from a bioethanol process and 60% hydrocarbon oil.

[0063] The samples labeled N7837 and N85651 are commercial crystal growth modifier products available from Nalco Company, Naperville, Ill. as Nalco Product Nos. 7837 and 85651, respectively.

[0064] Tables III and IV show the effect of Examples 1 and 2 on particle size of Bayer aluminum trihydrate and compare the performance of Examples 1 and 2, respectively, to the control (no CGM) and the commercial products N7837 and N85651, as described above. The +45.7 µm % fraction data listed is the average of triplicate samples. The samples were tested using duplicate runs at the equal dosage of 3 mg / m 2< seed surface (60 ppm vs. green liquor); the sample bottles were charged with equal quantities of seed; and the bottles were rotated and had equal holding times (test durations).Example 1 Test and Results

[0065] In the testing of Example 1, the liquor was fresh pregnant liquor with A / C=0.65; and the test temperature (precipitation temperature) during the holding time was 70 °C. The comparison results are shown in Table III. TABLE III SAMPLES DOSAGE , ppm QUANTILE PARTICLE SIZE % INCREASE IN MEAN OF CONTROL QUANTILE PARTICLE SIZE D(0.1) , µm D(0.5), µm D(0.9), µm +45.7 µm, % D(0.1), µm D(0.5), µm D(0.9), µm +45.7 µm, % Control 1-28.5450.2585.8959.71Control 2-28.8650.2685.0259.90Average 28.70 50.26 85.46 59.80 N78376031.3454.3491.3868.66N78376030.9353.6690.1169.08Average 31.13 54.00 90.75 68.87 08% 07% 06% 15% N856516030.9853.6189.9465.59N856516029.9252.2088.4263.13Average 30.45 52.91 89.18 64.36 06% 05% 04% 08% Example 16031.2054.3491.7166.55Example 16030.4452.9488.9766.44Average 30.82 53.64 90.34 65.49 07% 07% 06% 11%

[0066] The results in Table III indicate that Example 1, employing a biodiesel formula in accordance with the present invention, provides a %+45 µm fraction relative to the undosed control sample. The table further shows that the biodiesel formula outperformed commercial crystal growth modifier product N85651. Surprisingly, the biodiesel formula, despite using biodiesel rather than traditional active components, resulted in increased CGM activity which is comparable to that of commercial CGMs.Example 2 Test and Results

[0067] In the testing of Example 2, the liquor was fresh pregnant liquor with A / C=0.70; and the test temperature (precipitation temperature) during the holding time was 70 °C. The comparison results are shown in Table IV. TABLE IV SAMPLES DOSAG E, ppm QUANTILE PARTICLE SIZE % INCREASE IN MEAN OF CONTROL QUANTILE PARTICLE SIZE D(0.1), µm D(0.5), µm D(0.9), µm +45.7 µm, % D(0.1), µm D(0.5), µm D(0.9), µm +45.7 µm, % Control 1-31.7460.35103.1171.42Control 2-31.5257.00100.5169.17Average 31.63 58.67 101.81 70.30 N78376036.5862.84106.1478.05N78376038.4063.09101.8480.51Average 37.49 62.96 103.99 79.28 19% 07% 02% 13% N856516034.4259.83101.6774.10N856516035.0960.81103.0975.41Average 34.75 60.32 102.38 74.75 10% 03% 01% 06% Example 26037.3564.70109.3779.75Example 26038.3665.70109.6881.26Average 37.85 65.20 109.53 80.51 20% 11% 08% 15%

[0068] The results in Table IV indicate that Example 2, employing a crude corn oil formula in accordance with the present invention, provides a %+45 µm fraction relative to the undosed control sample. The table further shows that the crude corn oil formula outperformed both of the commercial crystal growth modifier products N7837 and N85651. Surprisingly, the crude corn oil formula, despite using crude corn oil derived from a bioethanol process rather than traditional active components, resulted in increased CGM activity which outperforms commercial CGMs.

Claims

1. A composition for enhancing the production of aluminium hydroxide crystal agglomerates from a precipitation liquor crystallization process, characterized in that the composition consists essentially of: a crude corn oil component, wherein the crude corn oil component comprises 1-10 percent by weight C16 and C18 ethyl esters, 50-95 percent by weight diglycerol esters and triglycerol esters of long chain fatty acids; and a carrier liquid, the carrier liquid comprising a hydrocarbon liquid, wherein the hydrocarbon liquid is a hydrocarbon oil comprising aliphatic or aromatic oil compounds chosen from the group consisting of paraffinic oils, naphthenic oils, mixed paraffinic and aromatic oils, the residue of C10 alcohol distillation, and mixtures thereof.

2. A method for enhancing the production and recovering of aluminium hydroxide crystal agglomerates from a precipitation liquor crystallization process, characterized in that the method comprises the steps of: (i) adding to the precipitation liquor an amount of 0.01 to 400 mg of a growth modifying composition / liter of precipitation liquor to increase the particle size of the crystal agglomerates of the crystal growth modifying composition, said composition comprising: 1-100 percent by weight of a crude corn oil component, wherein the crude corn oil component comprises 1-10 percent by weight C16 and C18 ethyl esters, 50-95 percent by weight diglycerol esters and triglycerol esters of long chain fatty acids and comprises 80 percent by weight or more weight mono alkyl esters including C16 and C18 ethyl esters, diglycerol esters and triglycerol esters of long chain fatty acids, and 0-15 percent by weight free fatty acids; and 0-99 percent by weight of a carrier liquid, the carrier liquid comprising a hydrocarbon liquid; (ii) distributing the crystal growth modifying composition through the precipitation liquor; and (iii) precipitating crystal agglomerates from the precipitation liquor, wherein the crystal growth modifying composition effectuates an increase in particle size of the crystal agglomerates recovered compared to a precipitation liquor crystallization process absent a crystal growth modifier.

3. The method of claim 2, wherein the crystal growth modifying composition comprises 98-100 percent by weight of the crude corn oil component.

4. The method of claim 2 or claim 3, wherein the crystal growth modifying composition consists essentially of the crude corn oil component or the mixture of the crude corn oil component and the carrier liquid, wherein the hydrocarbon liquid is a hydrocarbon oil comprising aliphatic or aromatic oil compounds chosen from the group consisting of paraffinic oils, naphthenic oils, mixed paraffinic and aromatic oils, the residue of C10 alcohol distillation, and mixtures thereof.