Ball mill 1456А of continuous operation for dry material grinding
Ball mill 1456А is designed for dry grinding of ore and non-metallic raw materials, construction materials of medium hardness. The mill belongs to the tube ball mills of continuous operation with central discharge of ground product.
The drum ball mill is used in ore-mining, mining and chemical and other types of industries.
The mill operates continuously in a various flow diagrams (open or closed cycle) with central material discharge and enables to give out homogeneous (in fineness) ground product by means of grinding bodies (balls and cylpebs).
Ball mill grinding capacity depends on characteristics of the milling material (hardness, grindability), input material lump size (up to 40 mm), material moisture (up to 0,5 %), grinding fineness, feeding uniformity, filling with grinding bodies and material.
Items included in the scope of supply:
Two-chamber drum lined with cast lined covers, charging cover, discharge section, two carrying rollers, central drive, charging chute.
Mill design: The drum is a steel hollow cylinder with inside liner plates preventing it from impact and attrition influence of balls and material. The mill drum is separated by an intermediate partition into two chambers: for preliminary and fine grinding. Preliminary grinding chamber is loaded with balls. Fine grinding chamber is loaded with cylinders - cylpebs.
The drum is closed from both sides by end covers – charging and discharge covers.
The covers are cast together with hollow journals. Support tyres are set onto the journals by which the drum rests on two self-installing carrying rollers.
Charging device consists of a charging chute and a loading screw with lead bars for material travel. Screw is inserted in the charging cover trunnion cavity and connected to trunnion ends by pins through the flange.
Screw with lead bars is mounted in a similar way on the discharge cover. Screw is connected to the discharge drum with a screen designed for separation of randomly passed lumps.
The mill is driven from the electric motor through the coupling, gear box and flexible coupling. The mill is charged with material through charging chute.
The material entered the mill is being ground with the grinding bodies and is transferred from the loading end to the discharge end under pressure of continuously fed material.
When the drum is rotating the material is going to discharge device and by means of a screw removed through the discharge branch pipe.
In terms of serial products upgrading works considering the recommendations of operating organizations the plant has worked out the design documentation for two-chamber ball mill 1456А in the version 1456А.00.00.000-04.
This version differs from the series-produced mills 1456А 00.00.000-03 at the moment by using the soft start device (SSD) of series HFR1160 (PRR1160), installed in the control cabinet.
SSD of series HFR1160 (PRR1160) – it is relatively budget-priced and high-technology product in modular version used for start-up and protection of three-phase asynchronous electric motors being a part of industrial plant drives. SSD has a double CPU controller, built-in display and a keyboard, space-saving self-cooled casing.
Soft start provides impact minimization mode for power supply and drive electric motor. Thus the soft start has the following advantages: - lowering starting current that increases reliability of the mill start. During the mill start-up the voltage drop and breakdown in circuits is decreased; - excess voltage in motor coil engine is absent.
The soft start of the drive and its possible soft stop also exclude hazardous impact affects on the mechanisms of the drive and the mill itself decreasing the wear of the rotation assembly units. Therefore the dead-time is decreased connected with the inspection and repair of the equipment, its operation period is increased providing costs saving for repair and maintenance.
More advantages of SSD:
-small overall dimensions and weight;
-easy to connect;
-various adjustments of start-up/stop;
-easy erection and putting into operation
-protection and control functions;
-lowering losses in SSD due to switching over the drive work from the device to bypass contactor after reaching rated rotation frequency.
Adjustments using SSD key-board:
*main controlled parameters: initial voltage; run-up time; stop time; starting current;
*soft start variants: soft start with increased current; soft start with decreased voltage; impact start (to maintain the high torque during the impact time set when start up аn eclectic motor with high inertia – recommended start-up);
*stop variants: free stop (industrial set); soft stop;
Quotation and performance data of the mill 1456А.00.00.000-04 are similar to the mill 1456А.00.00.000-03.
|Mill type||Ball, two-chamber|
|Rated drum working volume, m3||8|
|Drum inner diameter without lining, mm||1512|
|Drum length, mm||5600|
|Rotation frequency of the mill, rpm.||29|
|Overall dimensions (length х width х height), mm||12000х2600х2300|
|Mill weight with grinding bodies, kg||38530|
|Maximum weight of grinding bodies, kg *||11000|
|Installed power of electric motor, kW||132|
|Rotation frequency of electric motor, rpm.||730|
|Supply voltage, V||380|
|TU 4844-002-54028 986-2003 OKP code 484421|
* Grinding bodies are supplied separately.