METHOD FOR CRUSHING IN A CONICAL ECCENTRIC-DRIVE CRUSHER

PROCEDE DE CONCASSAGE DANS UN CONCASSEUR EXCENTRIQUE A CONE

English Abstract

The invention relates to methods for medium and fine crushing and can find the
widest use
in the building, mining-and-metallurgical and similar industries where
material crushing
processes in conical eccentric-drive crushers are necessary. The method makes
it possible to
cut down the crushing and reducing steps by increasing the crushing ratio from
4 to 30 in a
single plant, having integrated a fine crushing step and a first reducing step
into a single
process to substitute thereby at least two crushing plants for one. The method
is
characterized by a sequence of the conical eccentric-drive crusher operations
as follows:
first, setting the discharging slot size to zero, followed by charging the
crushing chamber
with the raw material, followed by starting the crusher, followed by
increasing the
discharging slot size to achieve the required productivity, and obtaining the
required grain-size
of the finished product by adjusting the rotational frequency of a drive
eccentric. The
discharge slot size is selected with taking into account that the greater is
the discharging slot
size, the greater is the clear opening of the crushing chamber and
consequently the intra-layer
destruction of the raw material, and the higher is the crushing process
productivity,

French Abstract

Cette invention se rapporte à des procédés de concassage moyen et fin et peut être utilisée largement dans l'industrie de la construction, dans l'industrie minière et métallurgique, de même que dans d'autres secteurs analogues de l'industrie qui font appel à des processus de concassage de matériaux dans des concasseurs à cône de type excentrique. Le procédé de cette invention permet de réduire le nombre d'étapes de concassage et de broyage en augmentant le degré de concassage de 4 à 30 dans une seule installation tout en intégrant l'étape de concassage fin et la première étape de broyage en un seul processus, ce qui remplace au moins deux installations de concassage par une seule. Le procédé de cette invention se caractérise en ce qu'il comprend une succession d'opérations de travail du concasseur excentrique à cône et consiste d'abord à régler la dimension de la fente de décharge du concasseur de façon qu'elle soit égale à zéro, puis à charger une chambre de concassage avec un matériau de départ, à mettre le concasseur en marche, après quoi la dimension de la fente de décharge est augmentée jusqu'à obtention de la performance requise, la grosseur requise du produit fini étant obtenue au moyen du réglage de la fréquence de rotation de l'excentrique de commande. La dimension de la fente de décharge est choisie en sachant que plus la dimension de la fente de décharge sera grande, plus la section de passage de la chambre de concassage sera grande, plus la force de concassage et, par conséquent, la cassure intracouche du matériau seront importantes et plus les performances du processus de concassage seront élevées.

Claims

5
CLAIM
A method for crushing in a conical eccentric-drive crusher, comprising:
setting a size of a discharging slot between crushing cones;
starting the crusher;
charging a crushing chamber with a raw material;
crushing the raw material;
determining a grain-size of a crushing product; and
correcting the discharging slot size to obtain a required grain-size of the
product,
characterized by
first, setting the discharging slot size to zero,
followed by charging the crushing chamber with the raw material and starting
the
crusher,
followed by increasing the discharging slot size to achieve the required
productivity
of the crusher, and
obtaining the required grain-size of the finished product by adjusting a
rotational
frequency of a drive eccentric.

Description

CA 02593968 2007-06-21
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WO 2006/068539
METHOD FOR CRUSHING IN A CONICAL ECCENTRIC-DRIVE CRUSHER
The invention relates to methods for medium and fine crushing in conical
eccentric-
drive crushers and can find the widest use in the building and mining-and-
metallurgical
industries.
To prepare metal concentrate from ore, it is necessary to crush and reduce a
piece
that is more than 1 meter to particles that are less then 0.1 mm. Mostly, 3 or
4 reducing
steps are used where conical eccentric-drive crushers are employed, followed
by three stages
of reducing in rod and ball mills.
Eventually, the crushing and reducing divisions of ore-mining enterprises take
up
almost 60 % of all types of costs. Further, inevitable over-reduction to less
then 20 pm
results in metal losses of near 15 %,
With this, transfer of the bulk of the disintegration process to the crushing
division
allows essential decrease of said costs and losses.
The crushing methods in the existing eccentric-drive crushers had no changes
from
the moment of their development in 1878. The compression ratio of a material
layer at a
crushing plane is limited by a drive excenter; therefore, an inner movable
cone cannot have
amplitude of vibrations different from a drive eccentricity. Hence, the
crushing ratio is not
higher than 6T7.
It is impossible to increase the number of eccentric revolutions in
traditional
eccentric-drive crushers because this would result in going the system out of
balance and
sliding the cone from the spherical support,
Thus, technological capabilities of eccentric-drive crushers are practically
exhausted,
and the efforts of designers are focused mainly at improvement in the
reliability of crusher
assemblies and enhancement of the automatic control in the system.
Known is a method for intensifying the operation of an eccentric-type crusher,
as
implemented in an apparatus (the USSR Inventor's Certificate Ns 589895 of July
9, 1974)
wherein a driving member is embodied as a lever whose ends are in an eccentric
and in a
cone body while a support is in a crusher housing. This gives double increase
of a crushing
force, which increases the crushing ratio up to 7=8, but still does not
provide a controllable

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ratio of compressing a material layer and limits further improvement in
technological
process parameters.
Known is also a method of improving process parameters of an eccentric-drive
crusher (the USSR Inventor's Certificate N9 625770 of April 25, 1977),
comprising: idle
starting the crusher; decreasing a size of a discharging slot down to a first
touch with an
inner cone; fixing the achieved slot size; and charging the crusher with a
mineral. The
method allows achievement of a minimum tolerable size of the discharging slot
due to
taking all radial clearances (about 4 mm total) up in an eccentric assembly
because of
pressing a cone shaft by a centrifugal force to an eccentric surface and
pressing an eccentric
to a cylindrical sleeve.. Such a method gives rise to the crushing ratio
already up to 7+8.
However, it is already impossible to gain the large effect in the known
eccentric-drive
crushers at preservation of the operation principle of the eccentric assembly.
Known is a method - taken as a prototype - for crushing a mineral, implemented
in a
conical eccentric-drive crusher wherein hydraulic regulation of an inner cone
position
(throughout a height) and of a discharging clearance value is provided (US
Patent Nn
3,456,889 of April 10, 1967, IPC B02C).
The method comprises: setting a discharging slot between crushing cones;
charging a
crushing chamber with a raw mineral; crushing the raw mineral; determining a
grain-size of
a crushing product; and correcting a size of said slot to obtain a required
grain-size of the
product.
Similar to the previous analogue, the prior art method is associated with
difficulties
in setting an accurate and -- possibly - small slot in order to obtain a
maximum crushing
ratio.
The present method as well as the previous one gives no chance to make the
crushing
ratio higher that 7-8.
It is an object of the inventive method to cut down the crushing and reducing
steps
by integrating at least two steps in one plant due to enhancement of the
crushing ratio.
A problem to be solved by the method is to organize such a sequence of
operations
that provide a high crushing ratio at the enhanced productivity and the
reduced specific
energy consumption.
Said problem is solved by that, in the inventive method comprising setting a
size of a
discharging slot between crushing cones, starting a crusher; charging a
crushing chamber
with a raw material, crushing the raw mineral, determining a grain-size of a
crushing

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product, and correcting the size of said slot to obtain a required grain-size
of the product,
there are operations according to the invention as follows: first, setting the
discharging slot
size to zero, followed by charging the crushing chamber with the raw material,
followed by
starting the crusher, followed by increasing the discharging slot size to
achieve the required
productivity, and obtaining the required grain-size of the finished product by
adjusting a
rotational frequency of a drive eccentric.
The method can be realized in a conical eccentric-drive crusher.
Figure 1 shows a longitudinal section of said crusher in the steady state.
Figure 2 shows a working part of the crusher in one of working conditions.
We shall understand the term "discharging slot" (reference numerals 11 in
Figures 1
and 2) as a sum of radial distances between bases of internal and external
cones.
Before the start of operating the plant, a size of a discharging slot (11) is
set to zero.
This makes it possible to charge a crushing chamber a row material that will
not get spilled
through the crusher without treatment, The start of the crusher takes place
after the charge
because it is known from the prior art that the idle operation of the crushing
plant is
undesirable since the friction of cones with each other results in the
premature wear thereof.
A necessary size of the discharge slot (11) is set with taking into account
that the greater is
the discharging slot size, the greater is the clear opening of the crushing
chamber and the
higher is the crushing process productivity. At the same time, such an
important parameter
as a grain-size of the finished product is monitored by adjusting a rotational
frequency of the
eccentric: change of this parameter makes it possible to adjust a value and an
application
frequency of a crushing force.
As contrasted to the offered technical solution, the initial (starting) size
of the
discharging slot in the similar methods is selected greater than that required
by the process.
This is made in order to decrease a load to a drive of the eccentric (8) when
the crushing
chamber is filled with the raw material. There is idle starting the crusher,
followed by
charging the raw material, followed by decreasing the size of the discharging
slot (11) down
to a required or minimal possible size depending upon a required grain-size of
the finished
product.
Figure 1 shows a structure of an eccentric-drive crusher.
The crusher comprises a frame (1) with an outer crushing cone (2) in which an
inner
crushing cone (3) is located whose shaft (4) is supported via a spherical
support (5)
(consisting of a pivot journal and an and thrust bearing) to a piston (6) of a
hydraulic
cylinder (7) located in the frame (1). An eccentric (8) is rotary mounted on
the shaft (4)

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within a bearing cylindrical sleeve (9) with a radial clearance (10) that is
higher then a size
of a discharging slot (11) between the cones (2) and (3).
The cylindrical sleeve (9) mates with an electrical motor (14) via a gear pair
(13).
An upper portion of the shaft (4) is located using a hinge (15) in a cross-arm
(16).
One side of a drive member (12) is rigidly secured on the cylindrical sleeve
(9) while
another side thereof is inserted to a groove (17) of the eccentric (8).
The crusher operates as follows.
The torque of the electrical motor (14) is transferred via the gear pair (13)
to the
cylindrical sleeve (9) which rotates the eccentric (8) by means of a system of
the drive
member (12) inserted to the groove (17). The latter develops a centrifugal
force and involves
the inner cone in circular vibrations. The cone (3) also acquires a
centrifugal force that is
summed with the centrifugal force of the eccentric to obtain a crushing force
due to which
the intra-layer destruction of the raw material takes place in a plane formed
by the crushing
cones.
By realization of the claimed sequence of operations, it is possible to adjust
the
crushing ratio within the range of 4 to 30. In other words, it is possible to
produce 100 % of
the product smaller than 20 mm or smaller than 5 mm from the same original
piece having a
size, for example, of 100 mm.
Thus, the method allows replacement of the fine crushing step and the first
reducing
step, for example, a rod mill, that is, allows solution of the problem posed
in full measure.

Representative Drawing