Aluminum industry carbon anode production requires high-quality calcined petroleum coke (CPC) that is low in sulfur and trace metal impurities such as V, Ni, Ca, Fe, and Si. These are typically controlled by maximum specifications set at the smelter level.
Carbon product prices remain volatile, and primary aluminum smelters are incentivised to seek long term solutions for the supply of anode grade pet-coke. This will help to mitigate the risk of spikes in carbon costs.
The counter pressure casting (CPC) process is emerging as a replacement for the low pressure die cast (LPDC) process. It is reported to offer superior quality in the production of aluminum parts as a result of the filling process occurring against back pressure during the casting cycle. The aim of this study is to investigate how this characteristic feature of the CPC process influences the fluid flow and heat transport phenomena during casting and its impact on part quality.
In-plant measurements were performed in a CITIC Dicastal commercial CPC machine configured for the production of automotive suspension control arms under two process conditions. Temperature data was measured from thermocouples (TCs) installed in the top die and bottom die. The temperature evolution during a cyclic steady-state cycle was investigated at six selected TC locations, i.e., TC3, TC9 and TC12 in the top die and TC36, TC42 and TC46 in the bottom die.
The results indicate that chamber pressure does not significantly influence the temperature field in the top die. During cycle 4 the temperature increases rapidly as the liquid metal enters and starts to solidify and decreases with the onset of part ejection.
As the demand for primary aluminum is strong, prices for anode-grade calcined coke are at new highs. Prices of Chinese CPC with 3pc sulphur and required metals specifications reached about 4,000 yuan/t ($3,618/t) on an ex-works basis at the start of this week.
The quality of anode carbon is crucial to aluminum smelting. Most smelters have their own carbon plant to produce pre-baked anodes. Using CPC as a feedstock for their carbon plants, they can control the quality of anode anodes produced.
The quality of anode-grade GPC varies depending on crude oil source and refining economics. Differences in bulk density, pitch level and particle size can result in a large variation in anode performance. The use of a blending system can help improve anode consistency.
Aluminum smelters require high quality coke as input material, with the quality of CPC directly influencing the quality of aluminum anodes. Coke quality is characterized by its VM content, which can be determined from the vibrated bulk density (VBD) test and its calcination method (rotary or shaft). Calciners typically prefer GPC with lower VM levels for better anode production, but this preference may be less important now that the global aluminum industry has adjusted to more stringent specifications for CPC.
The shuttle system in the aluminum casting process allows for quick mold changes by quickly and safely swapping out empty holding furnaces with full ones. This eliminates oxidation problems and guarantees our customers receive the cleanest alloy possible for their application. Moreover, it ensures the high productivity of the aluminum casting process for mass production of car wheels and other automotive parts. In addition, the shuttle system saves on energy consumption and lowers smelter operating costs.
The majority of Oxbow’s calcined petroleum coke (CPC) finds its way into primary aluminum production where it is used as a recarburizing agent. It is also widely used in the steel industry as a source of carbon. CPC is also a crucial ingredient in the process of producing titanium dioxide, which is used in paints, plastics, sunscreens and food coloring.
Trace metal impurities in CPC, such as V and Ni, impact aluminium purity, so it is important that they are kept low. Typical smelter maximum specifications for CPC are 2.5% S, 250 ppm V and 180 ppm Ni.
Rain CII Carbon’s wholly owned coal tar distillation plants produce metallurgical coke and coal-tar pitch, which are used to make anode-grade CPC for the aluminium industry. These facilities have strict environmental standards and are highly efficient. This helps to reduce energy costs and carbon emissions for the aluminium smelting process. This is particularly beneficial given recent warnings from China on industrial energy use in order to meet environmental goals and alleviate a shortage of coal and hydropower.
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