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[China]
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Address: No.2-A-609, NO.1 Longyu Road, Jianxi District, Luoyang, Henan, China
Contact name:David
Luoyang Zhongtai Industrial Co., Ltd. |
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Dry Fine Grinding Mills Rod Mill Machine for coarse grinding
Product Description
Rod mills are very similar to ball mills, except they use long rods
for grinding media. The rods grind the ore by tumbling within the
the mill, similar to the grinding balls in a ball mill. To prevent
the conditions leading to rod charge tangling, the length to
diameter ratio is maintained at 1.4 to 1.6. Rod mills accept feed
up to about 50 mm (2 in.) and produce a product in the size range
of 3000 to 270 mm (–4 to –35 mesh). Grinding action is by line
contact between the rods extending the length of the mill. Rods
tumble and spin in roughly parallel alignment simulating a series
of roll crushers. This results in preferential grinding of coarse
material and minimizes production of slimes.
Of the three main types of rod mill, overflow, end peripheral
discharge, and center peripheral discharge only the overflow mill
is in common usage. Wet grinding rod mills are normally used in the
mineral processing industry. Dry grinding is used in some areas;
however, it is confronted with problems and should be avoided
except where absolutely necessary. Rod mills operate at lower speed
than ball mills since the rods are rolled and not cascaded. For an
equivalent grind, a rod mill uses less steel than a ball mill
because of the lower speed and better contact between the media and
ore. The rod charge must be maintained in good working condition,
and broken and worn rods must be removed. Rod mills usually require
greater operator attention. It is important that the rods stay
essentially parallel to one another. If rods become misaligned,
grinding action is lost and, more importantly, rod tangles occur.
Maximum rod length is limited to about 6.1 m (20 ft). This in turn
limits the length, diameter, and capacity of rod mills. The heavier
rods acting upon the lifters and liners result in greater wear on
the mill liners.
Rod mills normally carry 35 to 65% rod charge by volume. The limits
on charge level are (1) keeping the feed end trunnion open so that
feed will get into the mill, and (2) keeping the rod charge low so
rods will not work their way into discharge openings where they can
cause rod tangling.
Rod mills Applications
The rod mill, a tumbling mill characterized by the use of rods as
grinding media, is used for grinding ores, coal/coke, and other
materials for both wet
and dry applications. The rod mill performs best when making
products having a top size of 4 mesh to 16 mesh operating in open
circuit, or as fine as 35 mesh operating in closed circuit with a
screen or other sizing device. The rod mill accepts feed ore as
coarse as 1 1/2” top size although better performance is obtained
by restricting ore feed size to 3/4”.
Materials too wet for fine crushing and dry screening may be wet
ground in a rod mill. Practice has demonstrated the ability of a
rod mill to dry grind damp materials that will pack or plug other
grinding equipment. and scrap loss are reduced by correct selection
of liners for the specific grinding duty. Additional
benefit results from use of a backing material, such as rubber
between the liners and the mill shell.
Feature
The cylindrical mill adopts the driving type edge-driving,
center-driving, edge-driving with multi-point meshing, etc; driven
by asynchronous motor +reducer +pinion and gear as well as
synchronous motor + air lclutch + pinion and gear.
Generally supported by static-dynamic pressure bearing on both
ends. Fuuly closed self-aligning 120º osculation rocker bearing is
used. Also single or double slipper staic- dynamic bearings can be
used. The bush is made by NC machine.
The large open gear is designed using AGMA standard, Equipped with
reliably sealed gear housing and grease ahtomatic spraying
lubrication system.
The shell is key part of a mill. Carry out finite element analysis
on it with computer to ensure the reliable operation;
The shell is automatically welded, ultrasonic inspected, wholly
annealed and machined by large special machine tools on one
chucking; there special seal on static-dynamic connection parts ,
ch as feed and discharge hoper, trunnion, etc, to prevent oil and
slurry leakage;
The liner is of wear-resistance material mad by our company, wich
has been specially heat-treated, with high hardness and long
service life. Also other wear-resistance casting or rubber liner
can be used;
There are slow speed drive for medium and large mill;
The high and low pressure lubricating station is equipped for
medium and large mill;
The control and protection system is controlled by PLC.
Historically, rod mills have been used as the first grinding stage
after crushing in mineral benefici ation circuits. The rod mill
product was further ground in ball mills before separation of
valuable minerals from the host rock. With the advent of
semi-autogenous (SAG) mills replacing secondary and tertiary
crushing as well as first stage grinding,the rod mill has fallen
out of favor for new large mineral beneficiation circuits.
A recent application for a trunnion overflow rod mill is in the
preparation of coal and petroleum coke slurries for Integrated
Gasification Combined Cycle electric power generation and
co-generation
facilities. The relatively coarse open circuit rod mill product,
plus the ability to not generate excess fines, is key to making a
high percent solids, low viscosity slurry capable of being pumped
directly into the gasification reactor vessel. This service has
been proven to be an excellent application for the traditional
design rod mill.
End peripheral discharge rod mills are used most frequently for dry
grinding operations. Grinding damp materials to moderately coarse
products in open circuit is feasible by using hot air, inert gas,or
combustion gases to air-sweep the rod mill.A recent new application
for the end peripheral discharge rod mills has been the preparation
of fuel for Circulating Bed Boilers (CFB). It is critical to have a
coarse product with the fewest amount
of fines for this product as the fuel mass must be fluidized by
combustion airflow. This same airflow will elutriate excess fines
from the fuel mass be-fore combustion is complete and reduce boiler
efficiency through loss of the fuel fines with the ash.
Rod Mill Main Technical Parameters:
| Model | Cylinder Diameter (mm) | Cylinder Length (mm) | Effective Volume (m3) | Mill Speed (r/min) | Load of grinding media (t) | Electromotor | Size (L×W×H ) (m) | Weight (T) | |
| Motor power (kW) | Speed (r/min) | ||||||||
| MB15×30 | 1500 | 3000 | 5 | 23 | 8 | 75 | 743 | 7.6×3.4×2.8 | 20 |
| MB17×30 | 1700 | 3000 | 5.8 | 20 | 10.2 | 90 | 980 | 7.6×3.5×3.1 | 40.4 |
| MB21×30 | 2100 | 3000 | 8.8 | 19.4 | 25 | 220 | 735 | 8.7×4.8×4.4 | 48 |
| MB21×36 | 2100 | 3600 | 10.8 | 21 | 28 | 220 | 735 | 9.5×4×4.7 | 52.5 |
| MB24×30 | 2400 | 3000 | 11.8 | 18.2 | 27 | 250 | 735 | 8.5×4.2×4.6 | 58 |
| MB27×36 | 2700 | 3600 | 18.8 | 17.5 | 42 | 400 | 187 | 12×5.7×4.7 | 70 |
| MB30×40 | 3000 | 4000 | 25.9 | 16.2 | 50 | 500 | 187 | 12.6×6.1×4.9 | 89 |
| MB32×45 | 3200 | 4500 | 33 | 15.5 | 56 | 630 | 167 | 16×8×5.6 | 111.5 |
| MB32×48 | 3200 | 4800 | 34 | 15.5 | 60 | 710 | 740 | 12×7×6 | 121.2 |
| MB36×54 | 3600 | 5400 | 50 | 14.5 | 97 | 1000 | 167 | 16×8×6.7 | 155 |
| MB38×52 | 3800 | 4200 | 54.1 | 14.2 | 102 | 1120 | 992 | 15×8.27×6.21 | 175 |
| MB38×58 | 3800 | 5800 | 60.3 | 14.2 | 112.2 | 1250 | 167 | 15.6×8.27×7.21 | 156 |
| MB40×60 | 4000 | 6000 | 70 | 14.0 | 130 | 1400 | 200 | 18.2×9.00×7.5 | 163 |
