Graphite Mineral Introduction
Graphite is an important non-metallic mineral resource, an
allotrope of carbon. Graphite is black-gray, soft, greasy,
chemically stable, corrosion-resistant, and does not react easily
with chemicals such as acids and alkalis.
Graphite Ore Beneficiation Methods
According to the characteristics of the original ore, the graphite
beneficiation process can be divided into the following two types:
Crystalline Graphite Beneficiation Methods
Crystalline graphite has good natural flotability, and flotation
methods are basically used for ore beneficiation. Since the size of
graphite flakes is one of its most important quality indicators, a
multi-stage grinding and multi-selection process is used in the
selection method to separate large flake graphite as soon as
possible.
Cryptocrystalline Graphite Beneficiation Methods
Cryptocrystalline graphite has very small crystals, so it is also
called microcrystalline graphite. Graphite particles are often
embedded in clay, which has poor floatability and is difficult to
separate. Due to the high grade of the raw ore (generally 60% to
80% carbon content), many graphite mines directly crush the ore,
hand-separate it, and then grind it for sale.
Graphite Flotation Beneficiation Flow
The beneficiation methods of graphite are flotation, gravity
separation, electric separation, etc. The most widely used method
is flotation. The specific steps are raw ore-crushing (coarse
crushing, fine crushing)-grinding-flotation-dehydration and
drying-classification-packaging.
The hardness of graphite ore is generally medium-hard or
medium-hard to soft, and the grade of the original ore is between
2-10%. The crushing process is relatively simple. It often uses a
three-stage open-circuit, two-stage open-circuit, or one-stage
open-circuit process. If it is small-scale weathered ore, it is
possible to grind the ore directly without crushing.
Since the hardness of graphite ore is generally medium-hard or
medium-hard to soft, and the grade is generally between 2% and 10%,
the crushing process is relatively simple, often using three-stage
open circuit, two-stage open circuit or one-stage crushing process.
Small and medium-sized mines, which mainly process weathered ore,
are directly sent to the ball mill without being crushed.
The flotation process is generally a closed-circuit process of
multi-stage grinding, multi-stage separation, and sequential (or
concentrated) return of middlings. There are three types of
multi-stage processes, namely concentrate regrind, medium ore
regrind and tailings regrind.
Crystalline graphite mostly adopts the concentrate regrinding
process, and the recovery rate of the beneficiation operation can
reach about 80% under normal circumstances. Some mines have also
tried the middlings regrinding process, but the effect is not
obvious. Some small factories also use open-circuit or
semi-open-circuit flotation processes, because too many tailings
are discarded. The recovery rate of beneficiation is very low,
generally only 40% to 50%.
In the drying process, the equipment is raised to a certain
temperature according to the need for heat, and the material in the
cylinder starts to be dehydrated in a large amount. The temperature
of the drying is constant as a whole. The graphite rotates
continuously with the rotation of the cylinder and exchanges heat
and finally plays an excellent dryness.
Under certain pressure, the density of the flotation slurry is
small, and the solid percentage content is low, so the
classification effect is good. The graphite is relatively depleted
in the sedimentation and relatively enriched in the overflow, which
is very beneficial to improve the regrind efficiency and the
efficiency of selection.
Due to the many times of grinding, a lot of medium ore will be
produced in the process. Medium ore generally contains a large
amount of graphite. If it is not processed, it will inevitably lead
to a decline in the recovery rate and cause a waste of resources.
Therefore, the separation of graphite medium ore is an
indispensable step in the graphite beneficiation process.
There are many processing methods for graphite middlings, mainly
the following: centralized return, sequential return, individual
processing, and multiple processing methods combined processes.
