Description

Tungsten & High-Intensity Wet Magnetic Separator

Wolframite minerals, being weakly magnetic with a specific susceptibility of 39×10 -6 to 46×10 -6 cm³/g, can be effective separated from cassiterite and other nonmagnetic minerals and gangue using a high-intensity wet magnetic separator (HIWMS). Recently, various versions of this machine made in China have been introduced in wolframite mines. For example, by using the SQC series HIWMS machine to treat the wolframite slime at a plant, a concentrate grade of 8.4% WO3 (concentration ratio of 19.2) with a recovery of 75.96% was obtained. The lower limit of effective recoverable size was found to be 10 µm (corresponding to wolframite size 5.3 µm) under a condition of maximum field intensity of 1.8×10 4 Os in the separation zone (Table 3). for cleaning and upgrading, various types of HIWMS are being employed to separate wolframite from cassiterite, apatite, scheelite, etc. for example, in another plant, using the SQC-Z-1100 type HIWMS and a rougher concentrate containing 44.72% WO3 and 1.3% Sn, a final product grade of 55.66% WO3, with 0.19% Sn was obtained at a recovery of 95.47%.

In addition, a new type of high-gradient magnetic separator (HGMS) has been used in tungsten ore processing. Treating a refractory slide which contains 27.55% WO3 53% Sn, and 74% minus 74-µm fraction, the machine gave a final concentrate grade of 63.98% WO3 and 0.4% Sn with a recovery of 82.65% WO3.

High Intensity Wet Magnet Separators

In recent years, the need has become more and more accute for a high capacity, high intensity, wet magnetic separator for the concentration of finely ground, paramagnetic minerals. As a result of this increased interest, extensive test work has been conducted at our Central Test Laboratory, and the basic design for such a separator has been established.

(a) The magnetic attraction of paramagnetic particles is affected by flux gradient produced within the particle.
(b) A magnetic pole, with sharp edges, produces a much higher magnetic gradient than spheres produce.
(c) Expanded metal sheets placed vertically, side by side, staggered, and reversed provide a multitude of magnetic flux concentrating edges.
(d) Test results indicate that for finer particles the flux converging media should have sharper poles and smaller voids.
(e) All three models of the high intensity, wet magnetic separators have the same magnetic flux uniformity and length of magnetic zone (maximum 8 inches).
(f) Operational and test work data have shown that the high intensity separator, with the expanded metal sheets, provides a high gradient and is remarkably efficient in the purification of ground and unsized silica sand, wollastonite, talc, clay, cassiterite, and in the concentration of hematite, ilmenite, and semitaconite ores.

In high intensity, magnetic separation, we are concerned with paramagnetic behavior of matter, and this is attained when the magnitude of magnetic moments is sufficiently large to more than compensate for the diamagnetic effect, which is always present. In a solid state sample this orientation process is seriously interfered with by magnetic delay T and temperature vibration.

The laboratory separator is constructed of two electromagnetic coils with a stainless steelbox (8 inches high x 2 inches wide x 1 inch deep) containing the flux converging element between the poles. One valve is located at the entry and the other at the outlet of the element box. A funnel is supplied for the hand, feeding operation.