NOVELTY - The process comprises separating iron-containing particles from a cutting slurry using a physical separation device to produce a slurry product, removing liquid from the slurry product to produce a powder mixture of silicon carbide and silicon, supplying the powder mixture such as silicon-containing material and iodine to a first vessel to produce silicon tetra-iodide rich composition comprising silicon tetra-iodide and vapor having silicon di-iodide, and supplying silicon tetra-iodide rich composition to distillation process to form an increased purity silicon tetra-iodide rich composition.    USE - The process is useful for recovering silicon from spent wafer-sawing slurry, where the recovered silicon is useful in the photovoltaic, microelectronic or semiconductor industries, for high-efficiency single-crystal solar cells and for reuse within the silicon-wafer based on photovoltaic industry.    ADVANTAGE - The process is capable of economically and efficiently recovering the silicon with high purity of 99.999999% and high throughput without any complex.    DETAILED DESCRIPTION - The process comprises separating iron-containing particles from a cutting slurry using a physical separation device to produce a slurry product, removing liquid from the slurry product to produce a powder mixture of silicon carbide and silicon, supplying the powder mixture such as silicon-containing material and iodine to a first vessel to produce a silicon tetra-iodide rich composition comprising silicon tetra-iodide and to produce a vapor comprising silicon di-iodide, supplying silicon tetra-iodide rich composition to a distillation process to form an increased purity silicon tetra-iodide rich composition, supplying the increased purity silicon tetra-iodide rich composition and the vapor comprising silicon di-iodide to a second vessel, where the deposited silicon is formed from the silicon di-iodide, purifying and recycling remaining silicon tetra-iodide from the second vessel, recovering the iron-containing particles from the separating step, adding a carrier gas to the first vessel in vapor supplying step to adjust the flow rate of the vapor-gas mixture, recovering silicon carbide particles from the first vessel, and recovering glycol oil or water from the slurry product. The silicon-tetra-iodide rich composition comprises silicon iodides and greater than 70% of the silicon iodides are in the form of silicon tetra-iodide. The silicon-containing material is prepared by a solid-liquid separation step, a magnetic separation step, a filtration step, a leaching step or a drying step. The silicon-containing material comprises metallurgical-grade silicon. The silicon tetra-iodide rich composition has a purity of 99.99999-99.99999999% (7-10 N). The first vessel is operated at 600-900 degrees C, the second vessel is operated at 900-1300 degrees C, and the distillation process is operated at a pressure of less than 101.3 kPa. INDEPENDENT CLAIMS are included for:    (1) an apparatus for recovering silicon;    (2) a process for recovering a wire-saw cutting slurry; and    (3) a system for recovering silicon.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of an apparatus illustrating the flow of materials for the commercial production of silicon and recovery of silicon carbide from a spent wafer cutting slurry.    Spent slurry (1)    Waste recycle stream (2)    Iron-free slurry (3)    Liquid stream (4)    Iron-free solid particles stream. (5)