Removal of lead from solid materials

Abstract

A leaching composition that substantially removes lead from solid materials and a method of using said composition. Preferably, the concentration of lead in the solid materials following processing is low enough that the solid materials can be reused and/or disposed of at minimal cost to the processor. Preferably, the solid materials comprise glass, such as cathode ray tube glass.

Description

FIELD[0001]The present invention relates generally to a composition that substantially removes lead from solid materials, and a method of using said composition.DESCRIPTION OF THE RELATED ART[0002]As the world transitions to flat panel televisions and flat panel computer monitors, more and more cathode ray tubes (CRTs) are being discarded. The safe disposal of CRTs present a serious environmental challenge since they contain leaded glass (primarily in the funnel, neck and frit) which may be readily leached from a landfill by acidic water. The lead content in the glass of a CRT can be as high as 20%, which means that a single 34″ television might contain more than 1 kg of lead. Lead is toxic and is known to damage the body's nervous and reproductive systems and kidneys. It can also cause high blood pressure and anemia. Lead is especially harmful to the developing brains of fetuses and young children and to pregnant women. As a result, lead has been banned from fuel, paint, pipes and ...

AI Technical Summary

Benefits of technology

[0007]The present invention generally relates to a composition that substantially removes lead from solid materials, and a method of using said composition. Preferably, the concentration of lead in the solid materials following processing is low enough that the solid materials can be reused and / or disposed of at minimal cost to the processor. Preferably, the solid materials comprise glass, such as cathode ray tube glass.

Problems solved by technology

The safe disposal of CRTs present a serious environmental challenge since they contain leaded glass (primarily in the funnel, neck and frit) which may be readily leached from a landfill by acidic water.

Lead is toxic and is known to damage the body's nervous and reproductive systems and kidneys.

It can also cause high blood pressure and anemia.

Lead is especially harmful to the developing brains of fetuses and young children and to pregnant women.

Recycling glass is manually intensive and expensive.

Waste disposal facilities receive glass waste that is not separated, and the waste disposal facilities have no effective techniques for automatically separating different glass wastes from one another.

Because of the expense and time consuming nature associated with recycling glass waste, many waste disposal facilities have resorted to the illegal disposal of glass waste.

A literature survey indicates that smelting recovers only 50% of the lead in the glass, produces toxic vapors and a contaminated toxic slag that is either landfilled (at high cost) or used as a low-value aggregate.

Therefore, the EPA realizes that it cannot permit the smelting process to continue indefinitely and is actively pursuing and promoting research to replace the process.

Since no truly viable solution to this problem exists, millions of tons of waste glass are being stockpiled by electronics recyclers looking for a solution.

Reuse is not a real option since relatively few new CRTs are being manufactured.

This problem will only get worse as liquid crystal and / or plasma screen technology is integrated into the industry and the at least 1.9 billion CRTs still in use worldwide are systematically disposed of.