The use of coal for the production of electrical energy has always had an inevitable consequence, the need to dispose of the ash resulting from combustion. Fly ash is a non-toxic waste product which is the result of combustion in coal fired generating facilities. The present invention provides a means of commercializing the ash produced in the combustion process by utilizing the fly ash and bottom ash produced in the coal combustion process to form compressed blocks which are suitable for use as construction materials.
The destruction of waste materials by incineration or combustion has gained favor in the U.S., despite some adverse public opinion. This method of disposal is generally less expensive than alternatives, and reduces the volume of the waste to be disposed. However, several problems exist with current technology. These problems are: (1) heavy metals are not removed and generally remain in the ash; (2) the ash produced is reactive and unmanageable; (3) particulate matter is present in the gas stream; and (4) reactant species in the gas stream may recombine to form toxic substances. The present invention addresses items 1 and 2.
The ash produced by waste incineration generally has a low density. The particles have a high surface area. These properties make disposal of the ash by ordinary means difficult. The high surface area increases chemical reactivity, and if water contacts the ash, it leaches out the heavy metal contaminants. This results in contamination of the water and creates a hazard for living organisms, including man.
The compositions, processes and products of the present invention avoid these problems through the encapsulation of hazardous materials into the fly ash bricks. This disposes of hazardous waste in such a manner as to prevent the hazardous waste from leaching into the environment. The process of present invention incorporates the hazardous materials into blocks formed of the fly ash composition of the present invention. These blocks have advantageous properties and are resistant to leaching.