Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Primarily organic continuous liquid phase
Reexamination Certificate
2000-11-20
2004-05-18
Metzmaier, Daniel S. (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Primarily organic continuous liquid phase
C106S123110, C106S123130, C106SDIG007, C162S171000
Reexamination Certificate
active
06737443
ABSTRACT:
FIELD OF INVENTION
The present invention relates to the processing of black liquor and the preparation of bitumen compositions containing black liquor.
BACKGROUND TO THE INVENTION
Black liquor is an aqueous alkaline pulping residue produced in Kraft pulping of wood chips in a pulp mill to provide wood fibers for paper-making. Black liquor generally contains about 55 to 65% solids comprising lignin, sodium salts of poly-saccharinic acids, organic and inorganic sulfides and carbonates and many other compounds. The lignin in the black liquor is the main organic component and is present as a high mass colloid stabilized by ionized phenolic groups. Lignin is a phenylpropane polymer of amorphous structure comprising about 17 to about 30% of wood. Lignin is so closely associated with the cellulosic fibres and hemi-cellulose that makes up the balance of woody material that lignin can be separated from wood only by chemical reaction at high temperature, such as that used in the Kraft pulping process, wherein wood chips are digested with an aqueous alkaline solution of sodium hydroxide and hydrogen sulfide, known as white liquor. Normally, the black liquor, after separation of the wood fibers, is processed to remove organic materials and to recover and regenerate pulping chemicals. Lignin can be recovered from wood-processing wastes only in limited quantities.
The lignin is a natural binder derivative of wood. Alkali lignin from both softwoods and hardwoods are useful in many products. They are used as stabilizers for asphalt emulsions, modifiers and extenders for latex emulsions, compounding agents in vinyl plastics, soil conditioners, binders in printing inks, wood stains, protective colloids in soap emulsions, dispersing agents for clay, fire foam stabilizers, drilling mud additives, insecticide dispersants, absorbers in storage batteries and foundry sand binders. Alkali lignin can also be used as adhesives for plywood, molding powers and formed insulating resins and as a reinforcing agent for rubber.
Asphalt binders (or bitumen) are widely used in different applications, such as asphalt-aggregate blends for road paving, asphalt fiber reinforced membranes for roofing and asphalt-water emulsions in surface treating both for paving and roofing. Problems for straight-run asphalt in those applications are the tendency to become brittle at low temperatures and to become soft at high temperatures, the tendency to flow under constant load at service temperatures and the tendency to phase separation during storage when mixed with other components.
Various approaches have been used for the purpose of improving asphalt compositions to address these problems. For instance, polymers have been utilized to improve the high and low temperature characteristics of asphalt compositions, as well as to improve their toughness and durability. Air blowing of straight-run asphalt has been used to improve stiffness and dimensional stability for hot applied roofing systems. The asphalt may be treated with acid to improve its compatibility with the polymeric additives. Lignin or lignin based additives have been widely used to emulsify asphalt to achieve a stable dispersion of asphalt in aqueous medium.
Black liquor is an aqueous colloidal system in which ample lignin is present. However, means have not been previously disclosed whereby a stable dispersion of lignin in asphalt can be achieved by combining black liquor with hot liquid asphalt. When the black liquor is added to the bitumen and dispersed with agitation into molten asphalt cement, de-watering of the black liquor occurs while lignin and other salts in the black liquor tend to form large, rigid aggregates which separate from the liquid asphalt and subsequently strongly resist dispersion in the asphalt.
It is the objective of the present invention to develop a process or processes whereby liquor-solid pulping residue (black liquor) can be converted from one in which water is the dispersing and plasticizing agent to one in which water is replaced by oil, achieving a dispersion in which a lignin based colloidal particulate phase is stably maintained. It is another objective to provide a lignin-oil dispersion which can be smoothly blended with liquid asphalt to produce a stable, homogeneous dispersion.
SUMMARY OF INVENTION
The present invention relates to compositions and methods for combining black liquor with selected petroleum-derived products. More specifically, this invention provides two separate processes for preparing lignin-based colloidal dispersions in lubricating or other petroleum-based oils. The lignin-oil colloidal dispersions prepared by either of such processes may be blended with bitumen to produce novel bituminous composition. Two embodiments of such procedures are described herein. The black liquor used in the invention may be that resulting from cooking wood in an alkaline solution in the soda or sulfate (Kraft) paper-making process.
The asphalt employed in this invention can be any of the well known bituminous substances derived from petroleum, shale oil, coal tar and the like. Commonly, the asphalt is prepared by vacuum distillation of a topped crude oil. Preferably, the asphalt has a penetration at 25° C. (as determined by ASTM D5) ranging for about 20 to about 400.
In a first embodiment of the invention, the procedure involves essentially two steps. In the first step, the black liquor is converted from its aqueous colloidal system to an anhydrous colloidal dispersion in a lubricating oil medium in which a surfactant, which may be an anionic surfactant, such as DDBSA (dodecylbenzene sulfuric acid), is used to promote the provision of the anhydrous colloidal dispersion. The process may be effected under low shear conditions.
The anhydrous colloidal dispersion of lignin in oil may be mixed, in a second step, with asphalt bitumen, producing a unique combination, which is a novel bituminous composition.
In another embodiment of the invention, the procedure again involves essentially two steps. First, bitumen is treated with an inorganic acid, such as sulfuric acid, at elevated temperature to provide an acid-treated bitumen. The black alkaline liquor is then added slowly to the acid-treated bitumen under agitation for de-watering the black liquor at a controlled rate to form a stable, substantially anhydrous, colloidal dispersion of lignin in the bitumen, also to provide a novel bituminous composition.
Accordingly, in another aspect of the present invention, there is provided a bituminous composition comprising bitumen, and dewatered lignin-containing spent alkaline pulping liquor dispersed therein. The dewatered spent alkaline pulping liquor may be present in an amount up to about 50 wt. % of the bitumen, preferably about 5 to about 25 wt. % of the bitumen.
In such composition, the dewatered spent alkaline pulping liquor may comprise an anhydrous colloidal dispersion of lignin in a lubricating oil. The dewatered spent alkaline pulping liquor may comprise a stable, substantially anhydrous, colloidal dispersion of lignin in the bitumen.
DETAILED DESCRIPTION OF THE INVENTION
Referring first to the first embodiment of the invention, a lubricating oil is mixed with black liquor at temperatures below the water boiling point. A surfactant, which may be DDBSA (dodecylbenzene sulfuric acid), is selected to be added to the mixture to facilitate the colloidal dispersion of black liquor in the lubricating oil while de-watering is gradually carried out at an elevated temperature. The dewatering may be effected by starting at an elevated temperature, which may be about 100° to about 180° C., preferably about 110° to about 160° C. The resulting cream-like paste product is miscible with hot liquid asphalt at any ratio to form a novel bituminous composition.
The lubricating oil used in the first embodiment of the invention may be a re-refined waste motor oil or other convenient petroleum-based oil. Contaminants of waste motor oil, such as dirt, lead, arsenic and other harmful metals and chemicals, are removed from the waste motor oil to produce a cl
Metzmaier Daniel S.
Polyphalt Inc.
Sim & McBurney
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