It is noted that manganese ore reserve in China ranks number 3 in the world. But it is much less than the reserve of the first two countries.
It has been more 100 years since Xingguo Manganese Mine, Hubei started its operation in 1890. At present, a great number of engineers in China
is engaged in prospecting, mining , beneficiation and ore processing. The technology of manganese mining, which has been developed greatly,
has its position in the world.
Manganese resource reserve
Till 1999, around 200 manganese mine in China were explored. It is known that there is hundreds millions tons manganese reserve in China. However, from the point of economy the recoverable manganese resource is 46% of the total reserve.
The geology characteristics of the Chinese manganese ore is characterized that the major ore body consists of marine deposit of manganese
carbonate, which takes more than 80% of the total reserve. The second is the layer controlled iron-manganese ore, the other ore like silver-
lead-zinc ore and weathered leaching manganese ore and the manganese ore body of volcanic rock characterized as small and complicated ore
Manganese ore bodies, mainly located in the province of Guangxi, Hunan, Guizhou, Sichuan, Yunnan and Liaoning in China distribute extremely uneven. There is less manganese ore reserve in the other places like coast areas and northwest areas.
The nature of manganese ore reserve is relatively poor. The average grade is 22%. Mn content in the ore of manganese carbonate is below 20%.
High grade ore and good quality ore is extremely deficient. Phosphorous content in the ore is high. Some ore is high phosphorous ore. Another
characteristics of the ore is high silica content. Some useful elements like iron. lead, zinc, cobalt, nickel, gold, silver, and etc. coexist in the
some ore body.
Most manganese ore bodies needs underground mining. However, most of the ore layer is thin and deep in underground mining and very hard to
mine. The complicated structure, the fine grains and high silica of the ore make great difficulties in mineral separation.
Each year China imports a considerable amount of manganese ore to supply the Chinese iron and steel industry.
There are hundreds of manganese mines. Most mines are small and medium in size. The average mining recovery is 80%-86%. The average ore
dressing recovery is 70%-75%. The general recovery is 60%-64%.
There are 3 mining processes – open pit mining, hydromining and underground mining.
(1) Open pit mining
There are not many open pits, such as Daxin Mine, Liancheng Mine, Xiaodai Mine, Jianshui Mine. The mines equip with drillers, loading machines and trucks. The level of most of the equipment is not advanced. Manual operation and part of manual operation are common in local small mines.
Few mines use hyrdomining process. Bayi mine and Dongxiangqiao mine used hydromining.
Underground mining is the major mining process. There are Zunyi Mine, Xiangtan Mine, Heqing mine, Dounan Mine, Huayuan Mine, Songtao
Mine. Most of the ore bodies are thin declined or gradually declined. The thickness and the angle along the direction varies significantly. The
other features are multi-layers, developed gap and unstable wall rock of roof and floor.
Based on the structure of the mines the mining process taken in most mines is openstope method. Some of the mines take the methods of filling
mining and caving mining. Initially, the major mining methods in stoping mining are methods of suspension roof support, shallow shrink and etc.
The disadvantages of them are backward stoping process and less mechanic operation. Innovation and improvement has been made in 20 years.
The improvement covers pre-support anchor prop(Zunyi), manual anchor prop(Heqing), anchor prop(Dounan), shallow shrink method and down section stoping process(Dounan Gakenan). It increased the recovery to a substantial extent and improved operation and safety.
Because of the limit of the mine nature the major filling methods are escapment, a few use hydraulic back-filling. The major processes in caving method are wall-caving and slicing and caving.
The regularity of ground pressure was studied with the research of underground mining process. It provided technical data for the
determination of structure parameters of mining areas and the treatment of worked-out section.
The progress in underground mining technology has been made. The typical ones are:
(1) The recovery is increased to 80%.
(2) Depletion and lean ore mixing has been reduced. The depletion has been controlled within 10% for low-angle dip and 12% for high-dipping. The quality of Mn ore has been improved.
(3) Mines are to be in normalization
(4) The backward process is eliminated. Work intensity has been improved significantly. Productivity has been increased.
(5) Regularity of ground pressure was revealed.
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 wasing. 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
Through arduous effort in 20 years we have made great success in the research of manganese dressing. The major 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