NOVELTY - A feedstock containing organic matter attached to insoluble solids is converted into a useful material by preparing a slurry from the feedstock; heating the slurry to produce a liquid mixture and solid material; removing the solid material; reacting the liquid mixture to produce a reacted feed; separatingreacted solid product, water, and reacted liquid product; and converting the reacted liquid product into a useful material in a second reaction.    USE - For converting a feedstock, e.g. food processing waste, turkey offal, municipal sewage sludge, beef paunch, animal manure, byproducts of food manufacture and distribution that contains organic matter attached to insoluble solids, and derives from an animal or its part from turkey, poultry, swine, fish, elk or cattle or animal was leaves, grass clippings, bagasse, seaweed, cotton waste, or animal waste, anthrax spores, infectious medical waste, and biological pathogens attached to insoluble solids into a useful material, e.g. carbon solids, carbonaceous material or mixture of hydrocarbons having fuel gas and oil, e.g. 2 heating oil (claimed).    ADVANTAGE - The invented method produces useful material in reliable purities and composition at acceptable cost and with high energy efficiency.    DETAILED DESCRIPTION - Conversion of a feedstock containing organic matter attached to insoluble solids into a useful material involves preparing a slurry from the feedstock; heating the slurry to produce a liquid mixture and solid material that includes the insoluble solids; removing the solid material from the liquid mixture; reacting the liquid mixture in a first reaction to produce a reacted feed comprising reacted solid product, reacted liquid product, and water; separating the reacted solid product, the water, and the reacted liquid product from the reacted feed; and converting the reacted liquid product into a useful material in a second reaction.    INDEPENDENT CLAIMS are also included for:    (a) an apparatus for converting a feedstock containing organic matter attached to insoluble solids into a useful material comprising a pre-treatment unit for producing a heated slurry from the feedstock wherein the heated slurry comprises a liquid mixture and a solid material that includes the insoluble solids; preliminary separation unit for removing the solid material from the liquid mixture; first stage reactor communicating with the vessel to receive said liquid mixture, and configured to subject the liquid mixture to a first increased temperature and a first increased pressure to produce a reacted feed; second stage separation unit(s) communicating with the first stage reactor to receive the solid product, liquid product, and water, and is configured to separate out the reacted solid product, the water, and the reacted liquid product; and third stage reactor communicating with the separation unit to receive the reacted liquid product, and is configured to subject the reacted liquid product to a second increased pressure and a second increased temperature to convert the reacted liquid product to a useful material; and    (b) a process for rendering animal body parts that contain organic matter attached to insoluble solids comprising preparing a slurry from the animal body parts; heating the slurry to 275-380degreesF to produce a liquid mixture and insoluble material; and separating the insoluble material from the liquid mixture.    DESCRIPTION OF DRAWING(S) - The figure shows the flow-chart of the process.