Abstrict An operational control method for a cylindrical crusher in which
furnace slag is supplied to the cylindrical crusher through supply
means and said furnace slag is crushed to obtain a furnace slag
product, wherein particle size distribution and iron content ratio
of a furnace slag product are detected and variable control of a
supplying amount from the supply means and/or revolution speed of
a cylindrical crusher is carried out within a predetermined range.
Claims What is claimed is:
1. An operational control method for a cylindrical crusher wherein
furnace slag is supplied to the cylindrical crusher through supply
means and said furnace slag is crushed to obtain a furnace slag
product, characterized in that said method comprises the steps of
detecting particle size distribution and iron content ratio of the
furnace slag product and conducting variable control of supplying
amount from the supply means and revolution speed of the cylindrical
crusher by a control device within a predetermined range.
2. An operational control method for a cylindrical crusher according
to claim 1 characterized in that said particle size distribution
is determined by a griddle separator and particle size measuring
means.
3. An operational control method for a cylindrical crusher according
to claim 2 characterized in that a sorted low grade product from
the griddle separator is separated by a magnetic separator into
a magnetic product of high iron content ratio and ore slag which
does not substantially include iron content.
4. An operational control method for a cylindrical crusher wherein
furnace slag is supplied to the cylindrical crusher through supply
means and said furnace slag is crushed to obtain a furnace slag
product, characterized in that said method comprises the steps of
detecting particle size distribution and iron content ratio of the
furnace slag product and conducting variable control of revolution
speed of the cyindrical crusher by a control device within a predetermined
range.
5. An operational control method for a cylindrical crusher according
to claim 4 characterized in that said particle size distribution
is determined by a griddle separator and particle size measuring
means.
6. An operational control method for a cylindrical crusher according
to claim 5 characterized in that a sorted low grade product from
the griddle separator is separated by a magnetic separator into
a magnetic product of high iron content ratio and ore slag which
does not substantially include iron content.
7. An operational control method for a cylindrical crusher wherein
furnace slag is supplied to the cylindrical crusher through supply
means and said furnace slag is crushed to obtain a furnace slag
product, characterized in that said method comprises the steps of
detecting particle size distribution and iron content ratio of the
furnace slag product and conducting variable control of supplying
amount from the supply means by a control device within a predetermined
range.
8. An operational control method for a cylindrical crusher according
to claim 7 characterized in that said particle size distribution
is determined by a griddle separator and particle size measuring
means.
9. An operational control method for a cylindrical crusher according
to claim 8 characterized in that a sorted low grade product from
the griddle separator is separated by a magnetic separator into
a magnetic product of high iron content ratio and ore slag which
does not substantially include iron content.
Description BACKGROUND OF THE INVENTION
The present invention is related to an operational control method
for a cylindrical crusher.
Most of blast furnace slag, convertor slag and electric furnace
slag or the like produced in the processes of iron manufacture and
steel manufacture had been disposed by throwing away. However, in
recent years because of decrease of reclaimable land and in view
of effective utilization of resources, recovery of an iron content
from slag and reuse of the slag for aggregate etc. have been practiced.
In this reason, by conducting such operations as a crushing process
for rough breaking or deformation of massive furnace slag and then
additional successive smashing process as well as sift sorting and
magnetic separation procedures and the like, a concentrate whose
iron content ratio is high is separated then withdrawn, and it is
reused as a slag product and also an aggregate. In addition, in
the crushing process of the rough breaking or deformation of the
massive furnace slag a swingable type crushing apparatus (U.S. Pat.
No. 4637562) or the like is utilized, while in the process of
the pulverizing or grinding of the slag of a cylindrical crusher
of a rod mill or the like is employed.
In such a way, the massive furnace slag whose dimension is greater
than 300-500 mm and whose iron content ratio is about 50-60% is
gradually decreased in size up to approximately 0-50 mm, and such
a furnace slag as having the iron content ratio of 90-98% can be
obtained.
The furnace slag is a non-uniform aggregation which is composed
of melt iron and fused ore slag etc. When the slag is under the
crushing operation, selective crushing proceeds in such a manner
that the crushing is developed from the boundary portion or the
like as the starting point where the iron content ratio is poor
but ore slag content ratio is rich and the strength is low, thereby
selectively crushing the furnace slag into one which has high strength
and a rich iron content ratio and the other which has low strength
and a poor iron content ratio. In this case, in the crushing process
the crushing operation is performed in a crushing circuit where
the supply means of the furnace slag and the cylindrical crusher
is connected in series, and furnace slag of a certain dimensions
is supplied to produce the furnace slag product with fine particle
size. The particle size of this crushed product depends on the supplying
amount from the supply means; the diameter and length of the cylindrical
crusher; configuration, dimensions and fill-up quantity of media
to be crushed; and the revolution speed of the cylindrical crusher
and the like. In an ordinal operation, when the properties and dimension
of the furnace slag are uniform, the particle size of the slag particularly
depends on the supplying amount from the supply means and the revolution
speed of the cylindrical crusher. The crushed product of the furnace
slag produced under such operations is further subjected to the
operations such as the sift sorting and the magnetic separation
and so forth, whereby the ore slag is separated from the crushed
product to be removed so that the furnace slag product which has
high iron content ratio can be obtained.
However, in the operational control method by the conventional
cylindrical crusher explained hereinbefore, there are such problems
that since the particle size distribution and the iron content ratio
of the furnace slag product is not detected directly and the supplying
amount from the supply means and/or the revolution speed of the
cylindrical crusher are not variable controlled by the control device,
when the properties, the configuration and the dimensions of the
furnace slag vary, the properties, the configuration and the dimensions
of the furnace slag produce may change remarkably, so that the furnace
slag which provides appropriate particle size distribution and iron
content ratio can not be produced efficiently.
An object of the present invention is to resolve these conventional
problems and to provide an improved operational control method for
a cylindrical crusher which can sufficiently effectively produce
a furnace product having appropriate particle size distribution
and iron content ratio to the substantial fluctuation in the properties
and configuration of the furnace slag, while variably controlling
the supplying amount from the supply means and the revolution speed
of the cylindrical crusher.
SUMMARY OF THE INVENTION
In order to accomplish the purpose described above, the present
invention is carried out in such a manner that particle size distribution
and iron content ratio of a furnace slag product are detected and
a supplying amount from a supply means and/or revolution speed of
a cylindrical crusher are variably controlled within a predetermined
range by a control device.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatical process chart of an operational control
method for a cylindrical crusher according to one embodiment of
the present invention.
FIG. 2 is an explanatory view of crushing characteristics in the
same method.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows a constitution of one embodiment of the present invention.
In FIG. 1 the reference numeral 10 designates the process of crushing
furnace slag and the numerals 11 12 and 13 exhibit furnace slag,
supply means and supplied furnace slag respectively, and the numerals
14 16 and 19 represent a cylindrical crusher, a griddle separator
and a magnetic separator respectively.
The furnace slag 11 is supplied to the cylindrical crusher 14 through
the supply means 12 and then the crushing of the slag is carried
out. The numeral 12a is variable driving means for regulating a
supply amount of the slag from the supplier 12 and the numeral
14a is variable driving means which enables to control a revolution
speed of the cylindrical crusher 14. The numeral 14b is a speed
reduction device. This crusher is provided with a sampling section
23 at a transfer passage for a furnace slag product 22 which is
of a sorted high grade product 17 collected through the griddle
separator 16 and a magnetic product 20 separated through the magnetic
separator.
The reference numeral 30 is a control device, and the sampling
section 23 is communicated with such a control device 30 through
particle size measuring means 24 and iron content analysis means
25. Outlet signals from the control device 30 are inlet signals
to respective control devices, which are not shown in the diagram,
of the variable driving means 12a and 14a.
Both of the supplying amount of the furnace slag 11 into the cylindrical
crusher 14 and the revolution speed of the crusher are variably
operated by the driving of the above-mentioned variable driving
means 12a and 14a which are controlled by outlet signals from the
control device 30 on the basis of present values stored in the device,
so that a crushed product 15 is discharged from the cylindrical
crusher 14. The crushed product 15 has been subjected to the effection
of the actuation of selective crushing, and in such a product a
portion as rich in iron content ratio and a portion poor in iron
content ratio are involved together. Succeedingly the crushed product
is supplied to the griddle separator 16 and then the shifting sort
for the crushed product is conducted to produce the sorted high
grade product 17 and a sorted low grade product 18 under the vibration
movement of a shifting surface in the separator. Because sorted
high grade product 17 is high in iron content ratio, it becomes
a part of the furnace slag product 22 without any process or after
passing through an additional process. Since the sorted low grade
product 18 is relatively lower in iron content ratio as compared
with the stored high grade product 17 it is further supplied into
the magnetic separator 19 for making magnetic separation to produce
a magnetic product 20 which is rich in iron content ratio and ore
slag 21 which does not substantially content iron, and then the
magnetic product 20 is admixed with said sorted high grade product
17 to produce the furnace slag product 22.
The furnace slag product 22 from the sampling section 23 is delivered
to the above-described particle size measuring means 24 and the
iron content analysis means 25 by an automatic sampler which is
not shown in the drawing.
Samples are continuously supplied into the particle size measuring
means 24 in which by the successive operations such as multistage
shifting operation and weighting operation and the like a gravimetric
frequency analysis in each particle size classification, i.e., a
particle size analysis is made to calculate and detect the gravimetric
frequency of the samples. If necessary, the processing of data such
as a largest particle size, a smallest particle size, 50% average
particle size and cumulative value is carried out in a short time.
While, in the iron content analysis means 25 the samples are supplied
there where by physical operations such as aquatic bulk specific
gravity measuring etc., the iron content ratio is calculated and
detected.
As a correlation exists between the iron content ratio obtained
by the particular analysis methods for the furnace slag product
and the results of the above aquatic bulk specific gravity measuring,
this relation may be utilized. As a result, also in the iron content
analysis means 25 the short-time determination of iron content
ratio of the furnace slag product becomes possible, and the detected
informations are inputted to the control device 30 and then they
are converted the output signals to be sent to the control devices
of said variable driving means 12a and 14a.
With regard to the measuring methods in the above-mentioned particle
size measuring means 24 and the iron content analysis means 25
employing a measuring method of a manual operation may be used in
place of said mechanical successive operations.
In the inherent characteristics of the process by the cylindrical
crusher 14 a quantity of the furnace slag which may be stored within
the cylindrical crusher 14 is relatively large so that capacity
delay can be expected, and the determination of said particle size
distribution and the iron content ratio of the slag can be established
in a short time, whereby the supplying amount from the supply means
and the revolution speed of the cylindrical crusher can be continuously
variably controlled within the predetermined range without giving.
Next, influence which is given no properties of the furnace slag
produce 22 by controlling of the supplying amount from the supply
means 12 and the operation speed of the cylindrical crusher 14
will be explained. In this case, the properties of the furnace slag
11 for example sorts of furnace slag, the iron content ratio, crushability
and the like, and also configuration or dimension etc. exert an
influence upon crushing performance.
When the steady operations for crushing the furnace slag 11 within
the cylindrical crusher 14 rotating at the predetermined revolution
speed under the predetermined amount of the furnace slag from the
supply means is conducted to produce the furnace slag product 22
if variation in the properties or the like of the furnace slag 11
takes place and such slag continues to be supplied, the crushing
sometimes advances more than it is required, so that the furnace
slag product 22 of grain which is rich in iron content ratio can
not be made. For this reason, the revolution speed of the cylindrical
crusher 14 is reduced to regulate the crushing. However, such a
operation makes reduction of the conduct capacity of the cylindrical
crusher 14. On the contrary, in combination with increase of the
supplying amount of the furnace slag from the supply means 12 this
problem can be avoided.
Then a predetermined range for the revolution speed of the cylindrical
crusher 14 is about 40-80% at N/Nc value. In this relation, N indicates
the revolution speed of the cylindrical crusher 14 and Nc represents
a critical revolution speed which is dominated by a diameter of
the crusher cylinder but controls moving condition of the media
to be crushed.
In the meanwhile, with regard to the relation between the sorts
and properties of the furnace slag and the crushing capacity of
the cylindrical crusher, the characteristic relation about various
kinds of furnace slag is enabled to estimate previously. Accordingly,
the characteristics may be memorized in the control device 30 and
characteristic values of samples taken out of the sampling portion
23 which are determined by the particle size measuring means 24
and the iron content analysis means 25 are inputted to the control
device in which necessary control calculation is carried out depending
on the above preset values and the characteristic values, whereby
the control signals to be sent to the variable driving means 12a
and 14a of the supply means 12 an the cylindrical crusher 14 are
outputted. In this way, the control device 30 can make the supplying
amount from the supply means 12 and the revolution speed of the
cylindrical crusher 14 operate variably within the predetermined
range.
FIG. 2 shows an example of a crushing characteristic of furnace
slag when using a cylindrical crusher.
The diagram designates that average particle size D50 (mm) and
iron content ratio (%) of products may vary in response to the variation
of the revolution speed N/Nc (%) of the cylindrical crusher.
The average particle size D50 means median diameter which corresponds
to central cumulative value (50%) in the particle size cumulative
curve.
In addition, the iron content ratio is changed from a value obtained
by the aquatic bulk specific gravity measuring.
Besides, there is no doubt that the constitution or arrangement
of the supply means, the cylindrical crusher and the control device
utilized in the present invention is not limited to those in the
above-mentioned embodiment.
In the present invention, as clearly understood from the above-described
embodiment, the particle size distribution and the iron content
ratio of the furnace slag product are initially detected, and during
the operation of the supply means and the cylindrical crusher which
are utilized for the crushing process the variable operation is
established, then the furnace slag product which provides appropriate
particle size distribution and also iron content ratio which correspond
to large fluctuation in the properties and the configuration of
the furnace slag can be produced sufficiently and effectively. Therefore,
the crusher can be operated for obtaining required grade depending
on respective applications of the furnace slag, and then such products
are made out.
Further, it can be recognized that a combination with additional
controlling operation of the supply means can make efficiently a
control range wider and so forth, thus the effects of the invention
are great. |