How to Reduce Cargo Carryback in Dump Truck Anti-Stick Liners for Nickel Ore Mining Operations? [New Energy Summit]

At the Battery Raw Material Forum of the 2025 (10th) New Energy Industry Expo hosted by SMM Information & Technology Co., Ltd. (SMM), Frisdio Fercanza, a geologist and mine research and development expert at PT Pamapersada Nusantara, shared insights on the topic of "Anti-Stick Liners for Dump Trucks in Nickel Ore Mining Operations." He stated that in nickel ore mining operations, it is crucial to keep the containers of dump trucks clean, as moist materials increase cohesion, forming sticky crusts that are harder to shed in the next cycle. More frequent cleaning of the containers can prevent carryback; maintaining a flat and undamaged floor is also important, as carryback may remain in uneven or damaged floor sections. Therefore, good maintenance of the container bottom is necessary; anti-stick liners can be installed at the bottom or throughout the container to minimize the formation of carryback. After unloading at the destination, more than 10% of the cargo remains stuck inside the container of a single truck. According to manufacturer standards, the dump truck containers are not designed with the characteristics of laterite ore, especially its stickiness, in mind. Without preventive or corrective measures, each truck will bring back a significant amount of residual cargo to the loading point. As the number of truck trips increases, this amount will also increase. Considering the number of trucks in operation, the total amount of material brought back will be enormous. In this case, a method is needed to prevent, reduce, and/or solve this problem. The current method to reduce carryback material is to equip each planned unloading point with a PC200 excavator in a 1:1 ratio with the main loading equipment. This auxiliary excavator will clean the container of each truck during unloading. This method has been proven effective in reducing carryback material inside the container. On the other hand, due to the need for a large number of PC200 excavators, additional fuel consumption, additional CO2 emissions, and increased truck cycle time (reducing fleet productivity), this method significantly increases mining costs. In this phase of the study, the truck containers need to be mapped. This will help establish a model of the residual material inside the container. To create this model, photos of the truck container will be taken immediately after unloading and before cleaning by the PC200 excavator to collect samples. The photo standards are similar to those shown in the slide below. The samples will be divided into three groups by material type: scrap, limonite, and weathered ore. The target number of samples (meeting specifications) to be collected for each group is at least fifty. The selection of liner material (metal bed liner) has been tested and results (metal bed liner) have been obtained. Anti-stick liners have been installed on two vessels using the final design. Vessel 427 is equipped with Hardox 450, while Vessel 433 is equipped with Bisclad 600. Both vessels were tested in hematite ore and overburden. What have we done? We tested the Bisclad600 container on unloaded limonite material in the stockpiling area. In this trial, we used the direct dumping method, and if the limonite could no longer slide, we continued with trimming, still requiring the help of an excavator. Results: During the trial, the limonite ore was very moist, making it very sticky in the container. The result obtained was that when directly dumped, the limonite started to shed after about 15 seconds. After that, loose material would cover the container bottom, causing the material to get stuck. The truck attempted to move forward several times after direct dumping, but there was still about 40% carryback. The entire dumping process until all material was completely shed took about 81 seconds. Results and evaluation of the Bisclad 600 liner: Evaluation: During the trial, the container was dirty as it was not cleaned before the trial. Additionally, the goethite material was moist after rain, making the material more sticky and difficult to shed. Therefore, the existing amount of carryback remains high. Thus, attention must be paid to the cleanliness of the container during use to avoid carryback. The wet conditions of the road and dumping area also need to be considered, as the equipment may become slippery when moving forward after direct dumping. Test results: Trial material Hardox 450 liner: What have we done? We tested unloading waste rock using the Hardox 450 container. According to previous recommendations, the back-and-forth method is not allowed. In this trial, we used the direct dumping method, and if the waste rock could no longer slide, we continued with trimming, still requiring the help of an excavator. Results: The result obtained was that when directly dumping waste rock, it started to shed after about 11 seconds. After that, loose material would cover the container bottom, causing the material to get stuck. The truck attempted to move forward several times after direct dumping, but there was still about 30% carryback. The trimming process was then performed by the excavator. The trimming process ran faster and easier as there was not much remaining material, and the liner helped the waste rock slide faster. The total process from the start of dumping until all material was completely shed took about 72 seconds. After the 10th trial, the waste rock adhered to the container wall, making it increasingly difficult to shed. Evaluation: From the following results, it can be seen that the scheme without trimming (back-and-forth method) takes longer, up to 2 minutes (Trials 1-3). The total time of trials using the direct dumping-trimming scheme is faster. In the fourth trial, the container was clean after cleaning. The result without the trimming process (only direct dumping) was about 40 seconds. This is because the container was in a clean state, so attention must be paid to the cleanliness of the container bottom. From the tests conducted, the material will start to slide at the 11th second (average). However, on the moist limonite material during the test, the material started to slide at the 15th second. This is faster than non-ASL vessels. The total dumping time of the back-and-forth dumping method is longer than the method of direct dumping followed by trimming. Compared to non-ASL, direct dumping takes about 72 seconds, while using only the trimming method (as usual) takes 60 seconds. Carryback itself starts to form in the vessel around the 4th to 6th cycle, which is also influenced by the material being transported. If the material is wet, it is easier to form carryback. Tests and results (spray method): In the first trial, spraying was conducted, and the dump truck had been cleaned before continuing to spray at the spraying point (maintenance station). The amount of spray released each time was about 5 liters, and the total spraying time was about 11-15 seconds. In the early trials, the dump truck was sprayed every cycle (vessel heads to the loading point → dumping point → spraying). Then, it was sprayed every 3 dumping cycles. The sprayed vessels included 427 with Hardox liners and 426 without liners. Summary and recommendations: 1. Pay attention to keeping the container clean, as moist materials increase cohesion, forming sticky crusts that are harder to shed in the next cycle. Containers can be cleaned more frequently to prevent carryback. 2. Maintaining a flat and undamaged floor is also important, as carryback may remain in uneven or damaged floor sections. Therefore, good maintenance of the container bottom is necessary. 3. Install anti-stick liners at the bottom or throughout the container to minimize the formation of carryback. 4. The unloading process also requires attention. When directly unloading, the material will fall, and then the truck slowly moves forward. It is necessary to ensure the area is safe to prevent the vehicle from slipping. 5. Use chemical spray (release agent) inside the container after a certain number of cycles to keep the container clean, with good sliding performance and no material sticking. Click to view the special report on the 2025 (10th) New Energy Industry Expo.