With the fast development of the refractory material and new energy vehicles, graphite resources are focused in recent years. There are two different type graphite: Artificial graphite and Natural graphite. Prominer provides the complete solution of graphite processing plant including crushing, grinding and flotation plant to make natural flake graphite concentrate. For graphite concentrate deep processing for anode material, we can also supply spherical graphite spherical grinding & shaping production system and spherical making test service. Besides, Prominer has various resources linking to chemical & thermal purification technology, coating technology, carbonization technology and half cell & full cell testing to make Li-battery anode materials and expandable / expanded graphite.
Every graphite mine has unique characteristics which need to be determined in advance. Therefore, it is of crucial importance to determine graphite flake morphology, primary flake size and liberation size. Typical flake graphite deposits are gneissic and consist mainly of feldspar, quartz and mica. The size of the graphite flake is a very important fact under commercial consideration. Therefore, it is in the best interest of a flake graphite producer to maximize the amount of large flake. Prominer is experienced in choosing the suitable grinding mill to reserve high yield rate of big flake graphite.
With the development of expanded graphite and anode materials industry, there is much requirement on high purity graphite product. It is very hard to reach the grade above TGC 96% just by the stage grinding and flotation processing. To get higher grade above TGC96% or even above TGC 99.95%, deep processing should be applied. General processing technologies for graphite ore are summarized as below:
Crushing & grinding solution
Stage grinding & flotation
Expandable / expanded graphite making
It is necessary to undertake the lab test or even pilot test for determining primary flake size and liberation size, improving the TGC grade as high as possible, meanwhile to find the suitable grinding-flotation way to reserve the big flake size graphite. It means that any processing reducing the size of constituent flake must be minimized. The ball mill is used for the primary grinding stage, thereafter the vertical stirred mill with ceramic grinding media is the best choice for intermediate regrinding stages.
Graphite purification furnace is used for continuous high temperature purification of graphite powder to match increasingly stricter environmental protection requirements. We have continuous type and pusher type for different purpose purification process. It is continuous loading and discharging under high temperature reducing the energy consumption and shortening the production cycle. The furnace adopts electrical resistant or induction heating that the temperature can reach up to more than 2600°C. Most of the impurities become gas, but the graphite will remain because of its heat resisting property. Both high temperature and chemical method can be used to satisfy the high purity requirement. The furnace uses high efficiency filter system, which can trap the dust and corrosive gases coming from the purification process.
Graphite used for high tech products such as Lithium ion batteries or fuel cells demands higher purity than typically upgraded by flotation. The chemical purification technology should be considered for further purification of graphite concentrate to TGC 99.99%. A basic process is thermal treatment in the presence of caustic reagents to dissolve siliceous impurities such as quartz, feldspar or mica. The graphite concentrate is mixed with caustic reagent and calcined at elevated temperatures. After calcination the graphite is leached with water washing away dissolved impurities. In order to get ultra-high purity graphite, the fine intergrown minerals residing between the graphite layers have to be removed. Thus, one or multi-stage acid washing with different acids or combinations is applied to remove impurities that are insoluble at alkaline conditions.
The spheroidization process is the most important step for making cathode & anode materials. Prominer has the ability to provide the complete spherical graphite grinding system including primary crushing mill, shaping mill, air classifier and dedusting system. It is widely used for processing cathode materials such as lithium iron phosphate, cobalt acid lithium, lithium manganate and Li-NiCoMn Lithium ion materials, and anode materials including natural graphite & synthetic graphite grinding and spheroidization processing. It is highly efficient to get potato-shaped graphite particles with high yield rate between 40-70%. We do also have the batch type shaper mill to improve the tap density.
As described above, spherical graphite needs to be processed by thermal and chemical purification for further coating and carbonization treatment.
For making the natural graphite anode materials, the coating and carbonizatino treatment are the key processing steps to determine the cathode and anode materials performance for rechargeable battery. Prominer maintains a good relationship with the suppliers that can provide coating and carbonization system.