Liquid purification or separation – Processes – Making an insoluble substance or accreting suspended...
Reexamination Certificate
1999-10-13
2001-02-06
Hruskoci, Peter A. (Department: 1724)
Liquid purification or separation
Processes
Making an insoluble substance or accreting suspended...
C210S727000, C210S928000
Reexamination Certificate
active
06183650
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to synthetic mineral microparticles, specifically metallic microparticles. This invention additionally relates to the production of such synthetic mineral microparticles, particularly to precipitation production of such microparticles by mixing metal salts and materials having precursor compounds.
This invention further relates to the use of both the synthetic mineral microparticles in water treating systems and the method of using such synthetic mineral microparticles in retention aid systems in paper-making systems.
BACKGROUND OF THE INVENTION
Traditional paper-making systems include the provision of a water-based slurry, termed a “paper furnish”, containing wood fibers, fines, and other ingredients to a moving web on a paper machine to facilitate the formation of a paper matrix, which is drained, dried and pressed into a final paper sheet product. A desire in such a process is to drain the excess water in an efficient manner to form a heterogeneous matrix without also unnecessarily removing desired fibers, fines and other solids. Retained undesired water burdens the downstream processes, such as, for example, a wet sheet in the dryer section. However, removal of desired solids endangers acceptability of the final paper sheet. Also, the act of draining water can adversely affect sheet formation.
Retention aid systems have been developed to increase retention of desired fibers, fines and solids, to improve paper sheet formation, and to drain better the paper matrix in the paper sheet forming section of paper machines. Such systems benefit, in part, the papermaker by allowing the paper machine to run more cleanly while producing a better sheet at higher machine speeds. Among the retention aid systems are those which utilize natural and synthetic microparticle systems. Certain of these retention aids include colloidal aluminum hydroxide, colloidal magnesium silicate, bentonite, colloidal silica, and organic polymer based systems.
Depending upon cost, quality, customer requirements and other considerations, the papermaker may employ a number of differing strategies of retention aid use. One typical strategy is to add an agglomerating agent to a thin stock precursor to the paper furnish. Such agent acts to agglomerate or flocculate the fibers, fines and solids. Typical agents are starch and/or polymers. However, such systems often subsequently subject the agglomerated material to a shearing force in screening equipment to produce smaller agglomerates with an intended purpose to obtain better sheet formation. A retention aid to help retain the fiber, fines and other desired solids can be added to the system before the furnish is passed through the paper machine head box to begin the paper matrix formation on the paper machine web. This retention aid causes a second agglomeration differing from the previous agglomeration.
Such aids have varying degrees of effectiveness due to the numerous variables in the paper-making process. One strategy is to formulate in a remote production facility various aids having a variety of relative percentages of the components. These differing percentages in the retention aid's composition are intended to match the requirements of the furnish for overall system performance. Such strategy often makes performance a result of art and happenstance rather than of engineered control. What are needed are better drainage aids and retention aids and methods of using such aids in the paper-making process.
Further, a system of agglomerating particles is sometimes useful in the treatment of water in trapping or otherwise removing undesired particles and oils or other globules from water. While many systems for water treatment exist based upon agglomeration principles, new and useful agglomerants are still desirable.
Accordingly, it is an object of the present invention to provide synthetic mineral microparticles, specifically metallic microparticles, which are new to the paper-making art and which provide equal or enhanced performance compared to present retention and drainage aids. It is a further object to provide a method for the production of such synthetic mineral microparticles.
Another object is to use the synthetic mineral microparticles in a novel method of production in paper-making systems by providing such particles as drainage and retention aids. In another aspect of the present invention, it is an object to provide a system of agglomeration useful in water treatment.
PRIOR RELATED ART
International Publication No. WO 92/20862 discloses a process for improving the production of paper and paper products by adding a cationic polymer and an amorphous metal silicate separately to the papermaking furnish with sufficient mixing between additions. The order of addition of these components is not critical, however, the preferred order of addition is to add the polymer prior to the last high shear point. Subsequently the amorphous metal silicate is added before feeding the resultant mixture to the headbox of a paper making machine without subjecting the mixture to any further substantial shear. Products produced according to the process of this invention are useful for increasing retention, drainage, and formation in the production of paper from pulp slurries.
U.S. Pat. No. 3,784,442 discloses the reaction of sodium silicate and aluminum sulfate in an aqueous medium. The resulting precipitate is subsequently filtered, washed and dried. Products produced according to the process of this invention are useful as pigments and moisture conditioners and are especially useful as rubber reinforcing materials and as a filler in papermaking.
U.S. Pat. No. 4,213,874 discloses a method for producing finely divided amorphous, precipitated alkali metal aluminosilicates having increased ion exchange properties. The products of the invention have base or ion exchange capacities equal to known crystalline zeolitic base exchanges or adsorbents and are useful as water softening and detergent additives.
SUMMARY OF THE INVENTION
The present invention provides a synthetic metallic microparticle composition comprising the product precipitated in the admixing of a soluble metal salt and one or more compounds having a component selected from silicates, phosphates and borates. The metal salts useable are selected from salts of metals in Group 2 of the Periodic Table (particularly beryllium, magnesium, calcium, strontium, and barium); the general transitional metals of Groups 3 through 12 (including lanthanides and the actinide elements); and various metals in Groups 13 through 17 (particularly aluminum, zinc, gallium, cadmium, germanium, indium, mercury, tin, thallium, antimony, lead, bismuth, and polonium). In one particular embodiment the silicate can be a silicate or an aluminosilicate, an aluminophosphatosilicate, or an aluminoboratosilicate.
In another aspect, the present invention achieves the production of the silicate by the reaction of a meta-silicate with a metal sale.
The present invention is also of a method for controlling drainage and retention in the formation of a paper matrix comprising the steps of admixing a soluble metal salt and one or more components selected from silicates, phosphates and borates, to form a reaction product; admixing the reaction product and a paper furnish to produce a modified paper furnish; retaining and draining a portion of the modified paper furnish on a paper machine wire to form a paper matrix; measuring the amount of such retaining and draining; and, on the basis of the measuring of the amount of retaining and draining, adjusting the amount of the soluble metal salt and/or the amount of the components selected from silicates, phosphates, and borates to effect a desired change in the amount of retaining and/or draining.
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of the present invention is a composition comprising the product precipitated in the admixing of a soluble metal salt and one or more compounds having a component (i.e. moiety) selected from silicates, phosphates and b
Hruskoci Peter A.
Minerals Technologies Inc.
Morris Terry B.
Powell Marvin J.
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