Purification of aqueous liquor

A process of separating coagulatable material from an aqueous suspension of the coagulatable material, the process comprising:

• providing a particulate, water soluble, ionic, polymeric coagulant that has intrinsic viscosity of 0.2 to 3 dl/g and that is in the form of dry solid particles that are individual particles or aggregates of particles,
• choosing a coagulant dosage of said solid particles from within the range 0.1 to 20 mg per liter of suspension,
• adding the chosen coagulant dosage of the solid polymer particles to the suspension,
• mixing the added polymer particles into the suspension and thereby dissolving the polymer particles in the suspension and coagulating the suspension,
• adding a counterionic organic polymeric flocculent solution to the coagulant suspension to flocculate the coagulated suspension,
• and subjecting said flocculated suspension to a separation process and thereby separating said coagulatable material from said suspension, and
• in which the counterionic organic polymeric flocculent solution is added to the coagulated suspension to promote flocculation of the coagulated suspension before or during said separation process, wherein the coagulant polymer particles have a size of at least 90% by weight between 100 .mu.m and 1000 .mu.m and are formed of monomers of which at least 50% by weight are diallyl dimethyl ammonium chloride, the coagulant polymer particles have a solubility such that they will substantially fully dissolve into the suspension in less than about a minute and said coagulated suspension is subjected to the start of said separation process within about a minute of the start of said mixing of the coagulant particles into the suspension, and the coagulatable material is selected from suspended solids and colloidally dispersed solids.

A process of separating suspended solids from coal tailings comprising:

• providing dry water soluble beads having a size at least 90% from 30 .mu.m to 1,000 .mu.m of a polymer having intrinsic viscosity 0.5 to 3 dl/g formed from 80 to 100% diallyl dimethyl ammonium chloride and 0 to 20% acrylamide and that have a solubility such that upon mixing the particles into the coal tailings they will substantially fully dissolve in less than about one minute,
• choosing a required coagulant dosage of the dry water soluble beads from within the range 0.1 to 20 mg per liter coal tailings,
• adding the chosen dosage of the dry water soluble beads to the coal tailings as the coal tailings flow turbulently from a mixing position to a flocculant addition position that they reach after not more than about one minute flow time and thereby dissolving the beads in the coal tailings and coagulating the tailings,
• mixing anionic polymer flocculant into the coagulated coal tailings at the flocculant addition position,
• and then allowing sedimentation of the solids in a sedimentation vessel and thereby separating the solids from the water of the coal tailings.