The ore dressing processes are gravity dressing, magnetic dressing and floatation. Because of the manganese ore exists in the form of fine grains it is hard to separate the monomer. Even though most of the monomer were separated it is difficult to solve the problem of the separation of the finest. Therefore, manganese ore dressing is aggregate dressing. So called aggregate is the mineral of relative high grade particles with coarse grains and easy to be separated. The disadvantage of it is low grade of concentrate.
(1) Washing and re-dressing
Manganese carbonate dressing with sprinkle on vibration screen (Hongqi zone of Xiangtan Mine)
Manganese oxide dressing with primary and secondary dressing in double screw trough washer(Dongxiangqiao Mine). Changsha mining institute developed a new process of self-grinding size degradation process. It combines the process of grinding, erasing and washing. It has been used in dressing of loose manganese ores. It is a creative development of dressing process.
The gravity dressing machine are jigging machine, shaking bed and high media drum separator, whirlcone, vibrating chute and etc. High media – intensive magnetic separation is used for manganese carbonate. Disposal of wall rock is in the first stage, deep separation is in the second stage(Xiangtan Mine).
(2) Magnetic separation
Intense magnetic separation is the most extensively and successfully applied process. It has been rapidly developed since China is open to the outside world. All of the major manganese mines applied the process. However, few of the mines use solely magnetic dressing. Most mines use combined process consisting of some of ore washing, gravity dressing, floatation and magnetic separation.
A lot of research work on magnetic separation has been carried out. The machine for separation of coarse, intermediate and fine particles, both permanent and electricmagnetic induction, were developed. Neodymium-iron-boron permanent magnetic is used in medium-intense magnetic field separator of PMHS series. The magnetic field intensity of separation is 1.1 T. The upper limit of separation is as high as 50mm. CS-1, CS-2 and shp-mode is a better applications. The upper limit of separation is 5-7 mm, the maxim intensity is 1488kA/m for CS-1 mode. The upper limit of separation is 10-15 mm, the maxim intensity is 1390kA/m for CS-2 mode. The upper limit of separation is 1 mm, the maxim intensity is 640-1600kA/m for shp mode.
(3) Floatation and others
Floatation dressing is not common in the Chinese manganese mines. Zunyi Manganese Mine used a joint process of intense magnetic and floatation. The chemicals of pertrolium sodium sulphonate and oxidized paraffin soap are used to catch rhodochrosite in floatation dressing. Chemical dressing, selective precipitation and concentrate dehydration and other process were studied. However, it is far to be applied in production. Through arduous effort in 20 years we have made great success in the research of manganese dressing.
The major ore progress is as follows:
(1) Pre-separation and coarse particles dressing. Intense magnetic dressing and gravity dressing of coarse particles are feasible for various ores of manganese carbonate. The recovery was 3%-5% increased thereby.
(2) Many types of intense magnetic dressing machine have been used. They are: 80-1, CGD-38, CS-1, CS-2, CGDE-210, PMHIS, shp and so on.
(3) Process of dressing of fine particles was successful.
(4) New process of comprehensive recovery of multi-elements manganese ore was successful.
(5) A lot was done on manganese mineralogy.
Mineral constituents of fine particles were defined by the quantity statistics of energy spectrum microprobe in the study of the states of manganese and phosphor and in the study of dephosphorization of high grade manganese ore. Forecast of theoretical specification of dressing was made by statistics of aggregate particles. Mineralogy studies were carried out in 9 big and medium manganese mines. The basic conditions required for dressing process and specification were provided.