Comparative Analysis of Flat - Mold and Vertical - Mold Casting Equipment for Silver Anode Plates

Abstract

This paper focuses on the core casting process of silver anode plates and systematically compares the process characteristics, product quality, and production efficiency of flat - mold and vertical - mold casting equipment. Considering the high thermal conductivity of silver (a material property where silver has a thermal conductivity of up to 429 W/(m·K), far exceeding that of metals like copper and aluminum), the causes of quality defects in flat - mold casting are analyzed. Moreover, the advantages of the vertical - mold constant - volume process in terms of dimensional accuracy, surface quality, and automated production are explained, providing theoretical support for equipment selection and process optimization in the industry.

Introduction

Silver anode plates are the core carriers in the electrolytic refining process, and their quality directly determines the electrolysis efficiency, product purity, and production stability. Casting, as a key step in anode plate forming, shows significant differences in quality control and production efficiency between flat - mold and vertical - mold casting due to their distinct process principles. Given silver’s high thermal conductivity (with a thermal conductivity of 429 W/(m·K), much higher than that of copper and aluminum), the heat exchange during casting is extremely intense, and the cooling rate changes non - linearly, which further amplifies the sensitivity of process parameters. Therefore, a thorough comparison of the technical characteristics of these two types of equipment is of practical significance for improving the quality of anode plates and meeting the requirements of electrolytic production lines.

1. Comparison of Casting Equipment Process Principles

1.1 Flat - Mold Casting

Flat - mold casting uses an open - faced planar mold, and the casting surface has a large surface area. After the silver melt is poured in, due to silver’s high thermal conductivity, the heat exchange rate between the melt and the mold is extremely fast (the cooling rate can reach 2–3 times that of conventional metals), resulting in a very short solidification process. Slight fluctuations in process parameters (mold temperature, silver melt temperature, and casting speed) can directly affect the filling ability and solidification uniformity of the silver melt, laying hidden dangers for quality defects.

1.2 Vertical - Mold Casting

Vertical - mold casting is based on the principle of constant - volume casting, and the volume of the molten metal is precisely controlled through a closed mold. The mold structure integrates the forming design of hanging silver hooks, enabling the integrated casting of anode plates. The process has strong 密封性 (sealability), and the flow of the silver melt is more stable, effectively avoiding the impact of external interference on the solidification process.

2. Comparison of Product Quality Characteristics

2.1 Analysis of Forming Defects

(1) Typical Defects in Flat - Mold Casting

• Corner Deficiency: When the mold temperature is too low, the silver melt is over - cooled, or the casting speed is slow, the filling ability of the silver melt drops sharply, and the solidification front cannot completely fill the mold cavity, resulting in the loss of the corners of the anode plate.
• Thickness Unevenness: Flat - mold casting relies on manual or semi - automated control, and it is difficult to stabilize the casting flow. In addition, the anisotropic cooling shrinkage of the silver melt easily causes thickness deviations on the plate surface (which can reach more than ±0.5 mm).
• Flash and Splashing: The open - type casting makes it easy for the silver melt to overflow into the mold gaps, forming flash and burrs. Moreover, the impact of the liquid flow during high - speed casting can also cause metal melt splashing, deteriorating the production environment.

(2) Quality Advantages of Vertical - Mold Casting

• Molding Integrity: The constant - volume mechanism ensures that the silver melt fully fills the mold cavity, and the incidence of corner deficiency defects is reduced to less than 0.5% (while it reaches 5%–8% in flat - mold casting).
• Thickness Uniformity: The constant volume makes the solidification shrinkage more uniform, and the thickness deviation of the plate surface can be controlled within ±0.1 mm, meeting the requirement of “uniform - thickness anodes” for electrolytic production lines.
• Surface Cleanliness: The closed - process significantly reduces flash and burrs (with a burr height ≤0.2 mm) and splashing, reducing the subsequent grinding cost.

2.2 Dimensional Accuracy and Functionality

Flat - Mold Casting: Drilling is required for the subsequent processing of hanging silver hooks, which not only adds processes (with a drilling accuracy error of ±0.3 mm) but also easily causes stress concentration. The weight deviation of the anode plate is affected by fluctuations in the casting amount, reaching ±2% (while it is only ±0.5% in vertical - mold casting).

Vertical - Mold Casting: Hanging silver hooks are directly formed, eliminating the drilling process and avoiding processing losses. The constant - volume characteristic ensures weight accuracy, and it can be adapted to the automated weighing and detection system, improving production coordination.

3. Analysis of Production Efficiency and Cost

3.1 Automation Level

Flat - Mold Casting: It relies on manual adjustment of the casting speed and mold temperature, and the parameter consistency is poor (with a deviation of ±5% for the same batch), making it difficult to achieve continuous production.

Vertical - Mold Casting: It supports full - automated control (including temperature closed - loop and flow closed - loop) and can achieve 24 - hour continuous production, improving the process stability by more than 60%.

3.2 Comprehensive Cost Comparison

Cost Dimension	Flat - Mold Casting	Vertical - Mold Casting
Equipment Investment	Low initial investment (simple mold structure)	High initial investment (complex constant - volume system)
Rejection Rate	8%–12% (caused by defects)	＜3% (stable quality)
Process Cost	Includes drilling and grinding processes	Integrated forming, no additional processes
Labor Cost	Requires 3–4 workers per shift	1–2 workers per shift (automated)

Although the initial equipment investment in vertical - mold casting is high, due to reduced rejection rates, simplified processes, and reduced labor, the long - term operating cost is 20%–30% lower than that of flat - mold casting, demonstrating a significant scale effect.

4. Conclusion

Vertical - mold casting, with its constant - volume process, integrated forming, and automation advantages, significantly outperforms flat - mold casting in terms of the quality of silver anode plates (thickness uniformity, surface integrity, and weight accuracy) and production efficiency. The high thermal conductivity of silver amplifies the parameter sensitivity of flat - mold casting, making its quality control extremely difficult. The industry should give priority to promoting vertical - mold equipment. Meanwhile, further research should be carried out in directions such as optimization of the temperature field and improvement of mold service life for constant - volume casting, so as to further tap the process potential and help the silver electrolytic refining industry upgrade towards “high precision, low cost, and intelligence.”