Research Stick Media Permutations High Gradient Magnetic Separation Process

High gradient magnetic separation (HGMS) of rod matrix, as one of the mostly effective methods for the concentration of fine and ultrafine weakly magnetic particles, is now widely applied for the concentration of fine weakly magnetic ores such as oxidized iron ore, ilmenite, wolframite, etc. and for the purification of non-metallic orese such as quartz, feldspar, kaolin, etc.The arrangement of rod elements in the matrix, as carrier for magnetic particles, has a dominant control on the distribution of magnetic field and the dynamic of magnetic particles in the matrix, thereby producing a significant effect the HGMS performance, which makes the arrangement of rod matrix in high gradient magnetic separation become one of the most significant theoretical problems. However, the existing works concerning the rod matrix in high gradient magnetic separation is mainly limited to the single rod element, and is focused on the magnetic capture of single rod element to magnetic particles. In some literatures accidentally reported on the real process of high gradient magnetic separation, the matrix is also regarded as the simple overlay of rod elements, with the complicated interactions of magnetic fileds between rod elements ignored. However, studies have confirmed that the predicted results based on the magnetic capture of single rod elements are far away from those of the practices, with exetreme guidance to the practice of real high gradient magnetic separation.Thus, an experimental approach entitled "Slice Matrix Analysis" method was proposed for the optimization of rod matrix. In the method, the matrix is artificially considered to consist of a number of slice matrices, onto which the magnetic captures of rod elements to magnetic particles are visible and measurable. Through the combinatorial optimization of rod elements, an optimum rod matrix may be designed in accordance with the characteristics of given material, and may also provide a theoretical foundation for the practice of high gradient magnetic separation.The theorectical investigations show that the magnetic force onto magnetic particles is closely related to the magndtic induction and the distribution of magnetic field in the matrix, and the distribution of magnetic field is dependent on the arrangement of rod elements, the spacing between rod elements in a single layer, the spacing between layers of rod elements, and the layer of rod elements, etc.The experimental investigations of pulsating high gradient magnetic separation of rod matrix with different combinations in concentrating fine hematite indicate that, the intersection arrangement achieves a better separation performance than that of rectangular one; it a weight0.96%higher, grade2.53%higher, recovery2.47%higher and tailings grade3.13%lower concentrate, than those of the rectangular arrangement, resulting in a separation effieicency8.24%higher than the rectangular arrangement. With increase in the spacing between rod elements in a single layer from4mm to5mm, the concentrate grade is increased from55.25%to56.47%, the concentrate weight is decreased from48.67%to44.08%, the tailings grade is increased from12.39%to14.95%, the iron recovery is decreased from80.87%to74.86%, and the separation efficiency is decreased from61.34%to58.63%. For a given layer of rod elements, the more is the spacing between layers of rod elments, the better is the separation results.Combining the theoretical and experimental results above, the combination of rod matrix has a significant effect on the separation performance of high gradient magnetic separation. With an optimum arrangement of rod matrix, the separation performance of high gradient magnetic separation may be significantly improved, and it is beneficial to the design of high gradient magnetic separators.