Chemical Industry Grinding Balls Case
German Chemicals: Fine Grinding
1. Overview
Our client is a large fine chemical enterprise in Germany, specializing in the production of products such as titanium dioxide for coatings and plastic additives. The plant is configured with six Φ2.2×5.0m horizontal ball mills, utilizing a wet grinding process to treat a mixed raw material of ilmenite and kaolin, with an annual raw material processing scale of 1.8 million tons.
2.Problem
As a compliance benchmark enterprise in the EU chemical industry, the plant demands extremely high standards for production process stability and environmental performance. However, due to the long-term use of ordinary high-chrome steel balls, the plant encountered numerous problems under the complex working conditions of “highly abrasive raw materials + corrosive media.”
3.Customer Request
- Solve the issue of corrosive wear of the steel balls and extend their service life to over 3,500 hours.
- Control metallic impurity contamination and ensure the whitenessof the titanium dioxide is consistently above 95%.
- Reduce annual downtime for media replacement to under 50 hours, thereby increasing capacity utilization to over 93%.
4.Chengda Proposal
The Chengda Wear-Resistant team conducted a 21-day on-site survey at the factory. Based on the operating parameters of the wet ball mill and the corrosive and abrasive characteristics of the raw materials, they proposed a customized solution: The “Cr24-Ni0.3 Corrosion-Resistant and Wear-Resistant Custom Steel Ball.”
- Core Enhancement: The chromium content was centrally increased to 24% to ensure the formation of a dense, stable passivation film on the steel ball surface, effectively resisting acidic media corrosion.
- A low nickel Ni content of 0.3% was added to refine the metallographic structure, enhancing the matrix’s corrosion resistance and toughness (preventing brittle fracture).
- Impurity Control: Carbon content was strictly controlled at 2.0-2.3% to reduce the risk of intergranular corrosion. S and P impurity levels were restricted to ≤0.02% (significantly lower than the industry standard of 0.06%), eliminating corrosion triggers at the source.
- Combination Process: A combined process of “Vacuum Induction Melting + Dual-Stage Isothermal Quenching” was adopted to prevent oxidation inclusions during melting and ensure the uniform distribution of Cr and Ni elements.
- The steel ball surface underwent “double-layer passivation treatment + precision polishing” to further enhance the adhesion and density of the corrosion-resistant layer.This results in a stable hardness of HRC 62-64 and an impact toughness of ≥4.8 J/cm², balancing wear resistance, corrosion resistance, and impact resistance.
- Based on an annual raw material processing scale of 1.8 million tons, the customized steel balls are projected to:Extend service life to over 3,800 hours.
- Reduce annual steel ball procurement costs by over 28%.Achieve a 100\% product compliance rate.
- We commit that if the steel ball life does not meet the standard, metallic impurities exceed limits, or energy consumption requirements are not met, we will resupply the steel balls free of charge and bear the losses from product rework and compliance penalties caused by downtime.
5. Monitoring System
- Inspect the corrosion status of the steel ball surface every 45 days (pitting depth ≤0.02mm, no obvious spalling).Calculate unit wear using the gravimetric (weight-loss) method.Test the corrosion rate of the steel balls in the simulated slurry using an electro chemical workstation.
- Collect finished grinding product samples every 12 hours.Detect the content of Fe³⁺,Cr⁶⁺ using an Atomic Absorption Spectrophotometer (AAS).Test the whiteness of the titanium dioxide using a whiteness meter (colorimeter), ensuring compliance with REACH Regulation and EN 71-3 Standard.
- Collect grinding mill current and energy consumption data in real-time.Log the frequency and duration of downtime for steel ball replacement.Evaluate the capacity utilization rate and carbon emission intensity.Formulate a “Corrosion & Wear – Product Quality – Energy Consumption” integrated analysis ledger (or dashboard/database) for correlation analysis.
6.Results Feedback
Monitoring data collected over 12 months of continuous stable operation showed the following key results:
- Corrosion, Wear, and Cost Effectiveness :The customized steel balls achieved an actual service life of 3,950 hours, representing a 79.5% improvement compared to the original standard high-chrome steel balls.The annual steel ball procurement cost was reduced by 32.8%.The unit energy consumption of the grinding mill decreased significantly, resulting in an annual reduction of approximately 1,260 tons of carbon emissions.
Product Compliance: The Fe³⁺ content in the finished product remained stable, and Cr⁶⁺ was not detected.The whiteness of the titanium dioxide improved to 95.5-96.0%.The product fully complies with the REACH Regulation and EN 71-3 Standard, and the customs clearance efficiency for exporting products to the EU market increased by 40%.
Operation Efficiency : The annual downtime for steel ball replacement in the grinding mill was reduced to 42 hours.The capacity utilization rate increased to 94.2%.The annual output of titanium dioxide increased by 108,000 tons.This success helped the client secure a long-term supply contract with a well-known European coatings company.
Currently, the client has signed a long-term supply agreement with Chengda Wear-Resistant Materials. Centering on this low-cost, corrosion- and wear-resistant solution, both parties will collaborate to establish a model benchmark for the optimization of grinding media in highly corrosive operating conditions within the fine chemical industry.
