The replacement of mineral sizer at a coal preparation plant in Indonesia
Overview
In recent years, with the refined development of coal preparation technology, coal preparation plants have higher requirements for the recovery rate of clean coal, product particle size and crushing efficiency, and the application of mineral sizer has also become more widespread.
The Baler Coal Preparation Plant is located on the island of Kalimantan, Indonesia. It was invested and constructed by the Indonesian KCL Company and is a modern coal preparation plant with an annual processing capacity of 10.00 million tons. The process system is divided into two parts: lump coal washing and fine coal washing.
The upper limit of the raw coal for washing is 200mm. Lump coal ranging from 200 to 13mm is sorted by a heavy medium shallow trough separator, while large lump coal over 80mm is crushed to below 80mm by a mineral sizer. The main product is medium lump coal (80 to 50mm). Small pieces (50-25mm), fine coal (less than 25mm), washed and mixed coal (less than 13mm), and coal slime.
The design index of the original lump clean coal mineral sizer in the coal preparation plant of Baler Coal Mine was that the output particle size was less than 80mm, and the proportion of washed medium lumps larger than 50mm in the product after crushing reached about 9.55%. With the changes in the market situation, the sales of washed medium lumps have been sluggish and the price per ton of coal is lower than that of washed small lumps and fine clean coal during the same period.
In 2022, in order to increase the comprehensive selling price of the product and maximize benefits, the coal preparation plant of Baler Coal Mine, in collaboration with the original equipment associated manufacturer, modified the tooth shape of the mineral sizer teeth and adjusted the output particle size of the lump clean coal mineral sizer from 80mm to 50mm to improve the product structure composition. However, the effect was not satisfactory.
After the renovation, frequent incidents of machine stalling and material blockage occurred, failing to meet the production capacity requirements. This affected the normal production of the coal preparation plant and the service life of the toothed rollers was short.
In the first half of 2023, the coal preparation plant cooperated with our company and decided to replace the original equipment.
Analysis of the cause of the malfunction
After investigation and technical verification, it was found that the first renovation plan of the customer’s mineral sizer was relatively simple and failed to carry out systematic optimization based on the overall logic and core requirements of the equipment operation.
During the renovation process, the intrinsic connection between the equipment’s material biting capacity and the crushing capacity was not fully considered. The material biting capacity is the foundation for mineral sizer to smoothly receive and convey materials, while the crushing capacity is the core goal of the equipment in handling materials.
The two need to be mutually compatible and work in synergy. If this point is ignored, even if adjustments are made to the local structure, it will be difficult to improve the overall performance of the equipment. At the same time, the two core parameters of the mineral sizer, namely the roller diameter and tooth shape, which directly affect the crushing effect and operational efficiency, have not been reasonably optimized.
The size of the roller diameter directly affects the grasping range and crushing torque of the equipment for materials. The tooth profile design determines the biting force and crushing method of the equipment for materials with different characteristics. The reasonable setting of the two is an important prerequisite for ensuring the stable and efficient operation of mineral sizer.
This renovation only focused on a single variable, namely the size of the tooth profile and the tooth spacing, and made blind adjustments merely to meet the surface requirement of reduced output particle size. This modification method has disrupted the balance and synergy among the original components of mineral sizer.
After the renovation, the equipment’s material biting capacity has significantly declined. When dealing with materials to be crushed, it is difficult to effectively grasp and stably convey them to the crushing chamber, resulting in the crushing process being unable to proceed smoothly. This further leads to a significant reduction in crushing efficiency, making it impossible to meet the rated production capacity standards designed by mineral sizer and unable to satisfy the material handling requirements in the actual production of customers.
Due to insufficient material biting capacity and reduced crushing efficiency, materials accumulate and remain in the crushing chamber, frequently causing machine blockage and material blockage accidents. This not only seriously affects the normal production progress but also causes additional wear and tear to the equipment itself, increasing the maintenance cost and failure risk of the mineral sizer.
Daily maintenance tips for Mineral sizer
In the production process of a coal preparation plant, mineral sizer is the core equipment, and its normal operation directly affects the efficiency and quality of coal processing. Therefore, conducting regular inspections and maintenance is a key measure to ensure the long-term stable operation of mineral sizer.
In order for the equipment to operate safely and stably for a long time, it is necessary to do a good job in the corresponding daily maintenance work. Regular inspection is a key part of daily maintenance work, which can ensure that mineral sizer can operate normally for a long time. Whether the components of mineral sizer can operate normally determines the subsequent operating status of mineral sizer.
Therefore, during the process of conducting regular inspection work, Targeted inspections must be carried out on core components. When conducting regular inspections, the specific inspection frequency should be determined based on the specific condition of the equipment and production requirements.
During the inspection process, it is also necessary to conduct targeted checks on key components and those prone to wear to ensure that the mineral sizer can operate safely and stably for a long time.
(1) Replace vulnerable parts: The vulnerable parts of the mineral sizer, such as the crushing tooth plate, crushing hammer head, liner plate, etc., need to be replaced within the specified replacement cycle to ensure the normal operation of the mineral sizer.
(2) Maintenance of the transmission system: The transmission system of the mineral sizer is the core component of the mineral sizer and requires regular maintenance and replacement. Especially components such as drive belts, gears and bearings need to be inspected and replaced frequently to avoid transmission system failures.
(3) Inspect the electrical system: The electrical system of the mineral sizer is an important component of the mineral sizer and requires frequent inspection and maintenance. Especially components such as motors, cables, and control systems need to be inspected and cleaned regularly to ensure the normal operation of the electrical system.
