Blue Circle Industries Plc

Welwyn Hall Research Association

Richard R Davidson

David Smith

Kenneth B Matthews

Christine A Beckett

Alban Timmons

An aqueous composition for conditioning an aqueous system, for example a sewage slurry, comprises an alkaline earth metal hydroxide, e.g. lime, and an anionic oligomeric polyelectrolyte, e.g. a salt of polyacrylic acid which composition has at least 40% by weight of particulate solid materials. Other components may include a weighting agent, e.g. calcium carbonate, a cationic flocculant, e.g. a polyacrylamide, and a base such as sodium hydroxide.

Process and composition for conditioning an aqueous system

An aqueous slurry of mineral particles, for example calcium carbonate and/or calcium hydroxide, has a mineral solids concentration of at least 40% m/m and contains an agent that maintains the slurry at a pumpable viscosity but that acts as a flocculant upon dilution of the slurry. Suitable agents include cationic and amphoteric polyelectrolytes having nitrogen-containing groups, for example polyamines and dimethyl diallyl ammonium chloride polymers. The slurries may contain other components, for example a synthetic hectorite or a dispersing agent such as a polyacrylate, polymethacrylate or polyphosphate. The slurries are useful in papermaking and in the treatment of sewage.

Compositions comprising mineral particles in suspension and method of

An aqueous slurry of mineral particles, for example calcium carbonate and/or calcium hydroxide, has a mineral solids concentration of at least 40% m/m and contains an agent that maintains the slurry at a pumpable viscosity but that acts as a flocculant upon dilution of the slurry. Suitable agents include cationic and amphoteric polyelectrolytes having nitrogen-containing groups, for example polyamines and dimethyl diallyl ammonium chloride polymers. The slurries may contain other components for example a synthetic hectorite or a dispersing agent such as a polyacrylate, polymethacrylate or polyphosphate. The slurries are useful in papermaking and in the treatment of sewage.

Acid reactive mineral particles are treated by dissolving certain hydrophilic organic polymeric compounds in the interparticulate water of an aqueous dispersion of the mineral particles and adding an interacting chemical to insolubilize the polymeric material and thereby form stable particle plus polymer agglomerates having a decreased rate of attack by acid. The acid protected particle plus polymer agglomerates are formed with a paper furnish into a paper sheet. A particularly preferred mineral is calcium carbonate. Suitable polymeric compounds are starch, sodium alginate, casein and alkali- solubilized latices. Sometimes it may be advantageous to use organic polymeric compounds in combination with one another.

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Cambridge, United Kingdom

Richard R Davidson