Managed composition of waste-derived fuel

DETAILED DESCRIPTION The above objects have been achieved by the present invention which provides a waste-derived fuel having a managed or designed composition of an ash residue, especially for fueling cement kilns, a method for preparing such a fuel, and a method of reducing carbon dioxide emissions especially from cement kilns.
The invention is based on particularly formulating the chemical composition of a fuel by blending proper proportions of a plurality of different selected wastes, so that the fuel has a desired fuel value (e.
g.
minimum BTU/lb.
) and a desired ash composition.
According to the invention, the specific composition of the fuel may be designed: 1) so that the ash composition is an approximation of the composition of normal raw material or process material less at least some of Ignition Loss (see e.
g.
Table 2, "Typical Raw Mix Composition for Cement Manufacture" below), and preferably the ash composition at least approximates the relative proportional content of the primarily significant elements Si, Al, Fe and Ca present in the normal raw material mix; 2) so that the ash composition is different from raw material or process material but contains a specific compound or compounds, for example iron oxide or silica, that are desired in the raw material mix, or process chemicals that are otherwise more expensive when not derived from waste, and preferably contains a higher proportion of such specific compound than is present in the normal raw material mix (see iron oxide in Example I, and Table 3 "Coal Fly Ash and Lime Waste" below); 3) so that the ash composition is different from raw material or process material in that it contains less than a typical or desired proportional amount of a compound, for example silica or calcia, that may be inexpensively added to the raw material by the cement plant or other process material preparation system, while it contains other essential materials to contribute to the raw material mix (see CaO in Example II and Table 4); 4) so that it includes calcium compounds other than carbonate minerals, as at least a part of the total calcium compounds provided in the mix, with a lower proportion of carbonates than are typically present in the raw material; 5) so that it includes a lower proportion of carbon per unit fuel value than a coal fuel that is being replaced