Flotation separation of lignosulfonates from the drain water of refractories factories

Abstract

placed in the upper part of the During floation the solution is pp. [368][369][370][371].Cleansing the drain water in refractories factories to get rid of surface--active agents of the anion type --lignosulfonates --is a difficult and commonly encountered problem [1]. The methods described in [2, 3, pp. 20-58, 4, 5] which have been recommended for use with industrial wastes are laborious (adsorption on heavy-metal hydroxides, activated carbon, and settling), or are uneconomical (ion exchange, dialysis, reverse osmosis, etc. ).In recent years more and more investigators such as [6, 7, pp. 112-117] have shown a preference for flotation for cleansing drain water to remove surface--active substances. Previously [8] it was shown that the effectiveness of the flotation process can be greatly improved by adding certain inorganic colloids to the solutions of surfactive agents, and also salts capable of forming relatively insoluble compounds with the surfactive agents.The present authors studied the possibility of using the flotation method for separating lignosulfonates and including it in the overall drain-water purification scheme of a department producing heat-insulating inserts.Drain water from the Pervouralsk Dinas Factory and model solutions of lignosulfonates obtained by diluting sulfite lye were the objects of the investigation; the sulfite lye (SSB) came from the Solikamsk Cellulose-Paper Coml~ne. The properties of the drain water and the sulfite lye are reported in [1]. The concentration of the lignosulfonates in the drain water and the model solutions was 100-200 mg/liter.The flotation process is carried out in a glass column 700 mm high and 30 mm in diameter. The bottom of the column consists of a porous plate (Schott filter No. 4). The volume of solution poured into the column is 100 ml. Air is fed into the column from the bottom through the porous plate; the air consumption (70-80 cm3/min) is controlled with a rotameter. The foam that is formed is collected in a special receiver column where it is destroyed. The volume of liquid thus formed is measured. analysed for the concentration of lignosulfonates using the standard method [9,The effectiveness of the flotation process in separating lignosulfonates was assessed from the degree of their separation from the solution and the concentration coefficient 7 in the foam product which were calculated from the equationswhere C O and Cp are the concentrations of lignosulfonates in the solution before and after flotation, rag/liter; P and C F is the concentration of lignosulfonates in the foam product, rag/liter.

About mechanism of foam stabilization by solid particles

“…The influence of solid particles on the foam drainage and stability can be diverse and strongly depends on shape and size of particles, its wettability and surfactant concentration [5,6].…”