Method for recycling the water used in a process for recovering glass from municipal waste

Claim 1

A process for the recovery of glass from the municipal trash which has been segregated into a glass-containing organic fraction and a glass-containing inorganic fraction comprising the steps of: (a) introducing the glass-containing organic fraction and the glass-containing inorganic fraction to a first water-based classifier, introducing water to the first classifier to entrain and separate the organic materials from the inorganic materials and leave a glass-containing inorganic mixture, discharging the water with the entrained organic materials to a first recycling means which includes first separation means to separate the entrained organic materials from the water, and thereafter recycling at least a portion of the water back to the first classifier; (b) discharging the glass-containing inorganic mixture from the first classifier, entraining the glass-containing inorganic mixture in a stream of water, transferring the glass-containing inorganic mixture and entraining water to a second classifier to remove particles greater than a first predetermined mesh size, passing the entraining water and particles less than the predetermined mesh size to a third classifier to remove particles less than a second predetermined mesh size and recovering a size classified glass-containing inorganic mixture, discharging the entraining water and particles less than the second predetermined mesh size to a second recycling means which includes second separation to separate the water from the particles, and thereafter recycling at least a portion of the water from the second recycling means to entrain the glass-containing inorganic mixture discharged from the first classifier and transfer it to the second classifier; and, (c) subjecting the size classified glass-containing inorganic mixture recovered from the third classifier to froth flotation in water in the presence of a beneficiating amount of a collector reagent for glass to form a water float containing predominantly glass and an essentially glass-free tailing, discharging the glass and entraining water to a third recycling means which includes third separation means to separate the major portion of the glass from the entraining water, said entraining water from said third separation means having suspended entrained particles, and fourth separation means to separate suspended, entrained particles from the water discharged from said third separation means and thereafter recycling a portion of the water from the third recycling means for use in the froth flotation and recycling a portion of the water to any one, two or all of the first, second and third classifiers, such process being further characterized in that none of the water recycled from any individual recycling means is returned to the process at a point downstream from such recycling means.