Carbon materials used in silicon metal smelting must be assessed against furnace technology, burden design and product-grade requirements. A standard semi coke analysis is only the first screening step.
Chemistry and impurity control
Fixed carbon establishes the principal carbon reference, while ash, phosphorus and sulfur require attention because non-carbon constituents may affect the burden and product-quality control. When impurity transfer is critical, request ash-composition data rather than relying only on total ash.
The Zhonghao catalog reference includes fixed carbon ≥84%, sulfur ≤0.3%, phosphorus ≤0.008% and ash ≤8%. These values support an initial discussion; they do not replace the buyer’s grade-specific acceptance limits.
Physical and electrical behavior
Silicon metal plants may also evaluate reactivity, electrical resistivity, mechanical strength and particle-size distribution. These properties are not interchangeable with routine proximate analysis. The required methods and target ranges should come from the buyer’s process experience or qualified technical program.
Particle size should match the furnace burden and material-handling system. Define fines and oversize limits, the measurement point and the method used to sieve the sample.
Why a controlled trial matters
Changing a carbon component can affect several interacting variables. A trial plan should identify the blend ratio, trial duration, baseline period and decision criteria. The plant may monitor burden permeability, furnace stability, electrical behavior, recovery, consumption and product chemistry. The appropriate metrics depend on the operation.
Build the RFQ around process fit
| Buyer input | Supplier discussion |
|---|---|
| Target silicon grade | Impurity and ash-composition requirements |
| Furnace type and burden | Size, physical properties and blend plan |
| Current carbon source | Comparison basis and trial objective |
| Sampling method | COA and third-party inspection scope |
| Quantity and destination | Packing, loading and commercial terms |
The safest purchasing approach is to screen the catalog data, request any additional application-specific tests and then qualify the material under controlled plant conditions.
Source register
- Zhonghao formal product catalogue, page 1, Semi Coke technical index
- Industry background: 外热式低阶煤热解与兰炭特性, https://mp.weixin.qq.com/s/bQ3yO5GHpmZ2v1bGfxEzNA