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(12) Patent Application Publication (10) Pub. No.: US 2008/0190861 A1 Branning (43) Pub

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(12) Patent Application Publication (10) Pub. No.: US 2008/0190861 A1 Branning (43) Pub US 2008O190861A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2008/0190861 A1 Branning (43) Pub. Date: Aug. 14, 2008 (54) COMPOSITION AND METHOD FOR Publication Classification AGGLOMERATING SOLIDS IN (51) Int. Cl SOLID-LIQUID SEPARATION PROCESSES Cori/52 (2006.01) (52) U.S. Cl. ........................................................ 210/728 (76) Inventor: Merle L. Branning, Plano, IL (US) (57) ABSTRACT An effervescent chitosan-containing solid composition for agglomerating Solids in and clarifying a slurry in a solid Correspondence Address: liquid separation process or system, Such as a mining pond, Edward O. Yonter E. a E. FE the Sosition is E. and Patent and Licensing Department claimed. The slurry contains water and solids. The composi Nalco Company, 1601 West Diehl Road tion includes chitosan, a solid acid, and a carbonate or a Naperville, IL 60563-1198 bicarbonate Source. Optionally, the composition is formu lated with an inert fluorescent tracer, to aid in dosing the composition to the slurry in the system. This clarification (21) Appl. No.: 11/674,804 process causes Solids to settle to the bottom of the pond, or otherwise aid in separating the Solids from the aqueous phase, leaving the water less turbid than before the application of (22) Filed: Feb. 14, 2007 chitosan. US 2008/O 190861 A1 Aug. 14, 2008 COMPOSITION AND METHOD FOR 0006 Chitosan (a natural organic biodegradable polysac AGGLOMERATING SOLIDS IN charide) has been identified as an environmentally friendly SOLID-LIQUID SEPARATION PROCESSES treatment scheme. Although usually fed as a dilute solution or in the gel form, it would be more advantageous to feed it in the TECHNICAL FIELD solid form. Its dissolution rate in solid form, however, is very low. If, for instance, the solubility rate could be increased 0001. This invention relates generally to a composition (enhanced dissolution rate), the use of chitosan as an envi and method for agglomerating Solids in Solid-liquid separa ronmentally friendly pond treatment clarification aid could be tion processes. More specifically, the invention relates to a made more effective and economical. Thus, there exists a composition including environmentally friendly chitosan that continued need for a method to quickly disperse the ultimate agglomerates solids from mining and mineral operation pond treatment of chitosan in a given pond system to affect efficient systems having a slurry with water and mined solids. The Solid/liquid separation. Additionally, the incorporation offine invention has particular relevance to a combination of chito silica or the like, can offer enhanced performance to this san, an acid component, and a carbonate or bicarbonate matrix by offering nucleation sites for the effective removal of Source that is characterized by improving chitosan dissolu hydrocarbons from a given pond system. tion rates in aqueous systems. SUMMARY BACKGROUND 0007. This invention accordingly provides a composition 0002 Pond systems are used in many industrial opera for dosing a solid-liquid separation system to agglomerate tions, such as mining of ores, minerals, and precious metals, Suspended Solids in the system. In one embodiment, the Solid certain chemical processing plants (e.g., production of clays, liquid separation system is a mining or mineral pond system. alumina, pigments, and paints), and some polishing opera The composition includes a first component and a second tions (e.g., sheet metal and silicon wafers). A problem asso component. The first component includes chitosan. The sec ciated with pond systems is that dispersed solids cannot be ond component includes a Solid acid and a carbonate source separated completely by conventional sedimentation or filtra and/orabicarbonate source in a ratio of about 1:4 to about 4:1. tion leading to problems including corrosion and Scaling of The ratio may be a weight ratio or a molar ratio. equipment, loss of product values in the Suspended solids, and 0008. In an embodiment, the composition is a dry blend of low product quality due to poor solids removal. Additionally, chitosan (first component) with an organic acid and a carbon fluids being discharged from a manufacturing plant to a pub ate orbicarbonate (second component). The chitosan may be lic water system must meet local requirements and the water in any suitable form, such as pellet, flake, powder, the like, in the pond systems may need to be treated prior to discharge and combinations thereof, according to alternative embodi from a plant or if the water content of the slurry is to be ments. This dry blend is characterized by a synergistic effect recycled. of enhancing a dissolution rate of the chitosan in an aqueous 0003. Many of these industrial processes, such as mining system. Adjusting the ratio of the first component to the and mineral operations, include Solid/liquid separation pro second component and/or the ratio of the organic acid to the cesses. Typically, a series of ponds (i.e., pond system) have carbonate or bicarbonate in the second component deter slurries including water and mined solids at the end of mineral mines the rate of dissolution of the chitosan and thus controls processing. Current industry practice is to add synthetic poly the treating of liquid/solid separation processes. The efferves mers to separate inorganic and organic Solids from slurries to cence (i.e., carbon dioxide gas release in Solution) provides allow recycling or discharge of process water used in these the dry chitosan a more effective surface area/water contact operations. The polymers act to agglomerate mined solids to resulting in controllable and enhanced dissolution rates. cause settling thus helping to clarify the slurry Such that the 0009. In an aspect, the invention includes a method of mined solids are separated from the water. agglomerating Solids in a Solid-liquid separation system. In 0004. The water may then be taken from the pond for an embodiment, the system is a mining or mineral processing either later use or addition/discharge to a natural body of pond system. The method includes controllably dosing Sucha water. Known synthetic polymers that are useful to clarify system with the chitosan-containing composition herein mining ponds include poly diallyldimethyl ammonium chlo described. In an embodiment, the method includes adding an ride (DADMAC), epichlorohydrin dimethylacrylate (EPT/ inert fluorescent tracer to the composition and using one or DMA), polyaluminum chloride/calcium chloride (PAC/ more fluorometers to detect a fluorescent signal of the inert CaCl), and the like. For example, U.S. Pat. No. 6,203,711 B1 fluorescent tracer. An amount of the fluorescent tracer that is to Moffett discloses a method of using a combination of present in the system is then determined and an amount of the silica-based colloid and anionic polymer to aid in flocculating chitosan present in the system based on the amount of the particulate material in aqueous streams from mining opera fluorescent tracer that is present in the system is calculated. tions. According to an embodiment, the method includes adjusting 0005. When the clarified water is discharged into the envi the dose of the chitosan-containing composition to ensure a ronment, however, it is desirable to employ environmentally desired amount of chitosan is present in the system. friendly treatment methods. While much attention has been 0010. In an aspect, the clarified water from a mining pond devoted to the general area of wastewater treatment and, more or pond system can either be returned to the mine or to the specifically treatment of municipal wastewaters, such treat mining processing plant for further use, or may be discharged ment methods may not be effective for industrial processing into a natural body of water. “LCs is that concentration of a wastewaters in terms of cost or providing acceptable water material in water that will be lethal to 50% of the test subjects quality. Therefore, there is a need for an efficient, cost-effec when administered as a single exposure over a set, typically tive system to clarify wastewater fluids present in inorganic over a 1 to 4 hour time period. Chitosan has been reported to and mineral processing. have an LCso for Daphnia of 463 mg/L and a LCso for Rain US 2008/O 190861 A1 Aug. 14, 2008 bow Trout of 155 mg/L. LCso information always has to be includes a plurality of ponds and the dose of the Solid com reported in units of mass per Volume of water and also has to position is individually adjusted for each pond. be reported relative to a specific test subject. These LCso 0019. In an embodiment, the invention is a solid compo results indicate that chitosan has been found to be of relative sition including a chitosan material or component. The chi low toxicity to aquatic organisms. This is an especially valu tosan component may be native chitosan, modified chitosan, able feature of the instant claimed invention in those instances chitosan salts, and the like. In another embodiment the chi where the chitosan travels with the clarified water into a tosan is chitosan lactate. Chitosan is a partially or fully natural body of water, rather than settling with the mined deacetylated form of chitin (a naturally occurring polysac Solids. charide of poly-D-glucosamine), which is the principal con 0011. It is an advantage of the invention to provide a stituent of the shells of crustaceans, such as crabs, lobsters, composition that enhances the dissolution rate of chitosan in and shrimp and many insects. an aqueous System. 0020 Chitosan is also described chemically as a deacy 0012. It is another advantage of the invention to provide a lated derivative of chitin. Chitosan monomers have the for biodegradable and environmentally friendly composition for mula CHNO, and each chitosan “unit has a molecular agglomerating solids in a Solid-liquid separation process, weight of 161 atomic mass units (“a.m.u.).
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