Systems and processes for pyrolyzing contaminants on foundry sand and combusting the resulting gas

A combustion process comprising:

• (a) providing a rotary kiln capable of roasting foundry sand containing contaminants, said rotary kiln comprising a container capable of being rotatable about an axis, said container having at least one side wall, at least one front wall defining an inlet port and at least one back wall defining an outlet port, with said inlet port being designed to readily accommodate or remove at least one oxygen-fuel burner and a porous plug;
• (b) providing foundry sand containing contaminants in said container;
• (c) inserting at least one oxygen-fuel burner in said inlet port;
• (d) injecting fuel and oxygen into said at least one oxygen-fuel burner wherein the amount of said oxygen injected is at least 50% greater than a stoichiometric amount;
• (e) firing, from said at least one oxygen-fuel burner, a flame and excess oxygen into said container;
• (f) ceasing said firing;
• (g) removing said at least one oxygen-fuel burner from said inlet port;
• (h) inserting a porous plug, which is in fluid communication with an oxidant source, in said inlet port;
• (i) tilting said container so that said porous plug is capable of dispersing oxidant at an angle ranging about 0.degree. to about .+-.30.degree., measured from vertical and so that said axis is at an angle ranging about .+-.0.degree. to about .+-.30.degree., measured from vertical;
• (j) rotating said container about said axis;
• and
• (k) passing oxidant from said oxidant source to said container through said porous plug.

A combustion system capable of roasting foundry sand containing contaminants, said combustion system comprising:

• (a) a rotary kiln comprising a container, a circular frame for surrounding and supporting said container so that said container is capable of rotating about an axis, a means for rotating said container coupled to said circular frame and a base pivotally coupled to said circular frame, wherein said container has, at least one side wall, at least one front wall defining an inlet port and at least one back wall defining an outlet port;
• (b) a means for combusting foundry sand selected from the group consisting of a porous plug for distributing oxidant into said container or an oxygen-fuel burner for firing a flame and excess oxygen into said container, said means for combusting being designed to be fitted into and/or fastened to said inlet port of said container;
• and
• (c) an off gas oxygen analyzer in fluid communication with said outlet port of said container.