**Editor's Note:** In China, where the mechanical processing, defense, and metallurgical industries are growing rapidly, corundum and silicon carbide play an irreplaceable role as abrasives and refractories. However, with severe overcapacity in the market today, the industry is facing a critical choice between survival and development. The three major challenges—energy consumption (including resource recycling), raw material sourcing, and environmental protection—are key to breaking through the current constraints. Among these, environmental protection is the top priority.
In the 1960s, the abrasive industry was dominated by a few large enterprises, while most were small or micro-scale companies under local industrial bureaus, all enjoying good economic returns. Over the past few decades, as the national economy expanded and the economic system evolved, the industry saw a massive increase in production capacity and output. However, the production methods, techniques, and equipment have remained largely unchanged. Corundum and silicon carbide smelting still rely on traditional technologies such as dumping furnaces, fixed furnaces, and electric resistance furnaces. Domestic grinding wheels cannot match high-speed, high-efficiency foreign alternatives, and most production remains semi-mechanized.
Today, the industry faces serious issues: rising labor costs, declining profitability from large-scale workshops, and severe pollution that not only affects worker health but also causes public concern due to dust emissions and smog. As a result, the abrasive and refractory industry must now prioritize technological innovation and environmental protection.
Based on long-term experience in the industry, here are some preliminary thoughts:
**1. Environmental regulations for the abrasive industry should be neither too low nor too high.**
According to national standards, an indoor emission concentration of 10mg/m³ is acceptable for workers to work without getting dirty after an eight-hour shift. The outdoor standard of 30mg/m³ is similar to that of the metallurgical sector, ensuring that smoke from chimneys is not visible to the naked eye. While this standard isn't overly strict, achieving it requires significant investment, sometimes even exceeding the cost of major equipment.
This level is just the minimum required for human survival. As living standards improve, stricter regulations will inevitably follow. For instance, the World Health Organization’s air quality standard for dust is 50μg/m³ or less—about 1/600 of the current outdoor standard. Since the sky is a shared space, emission limits will continue to tighten. If the abrasive industry adopts stricter environmental rules, it must consider both corporate investment capacity and the feasibility of technical implementation.
**2. Boldly eliminate outdated granulation methods.**
Traditional pickling and washing processes that generate dust at the source should be replaced with clean-blowing technology, a method already adopted in advanced countries like the U.S. Many Chinese design institutes have stopped designing pickling and washing lines, which is a sign of progress. Today, the focus is on dust control at the source, preventing dust from spreading to other stages. For example, dust generated during crushing is removed immediately, eliminating airborne particles during screening—a highly effective way to improve the environment.
**3. Reassess traditional dust removal methods based on current needs.**
Ten years ago, water curtains and electrostatic precipitators were significant improvements for factories without dust control systems. However, their efficiency is now insufficient to meet new standards. To achieve 10mg/m³, purification efficiency must exceed 95%. The only national standard that can meet this is the bag-type dust collector, which includes bag filters and cartridge filters. Cartridge filters, though limited to temperatures below 110°C, are gaining popularity internationally due to their compact design, long lifespan, and ease of maintenance.
Recent data suggests that Coulomb electrostatic dust removal could boost efficiency by 30% or more, reaching over 90%. However, no confirmed cases exist yet in the abrasive industry for meeting the 10mg/m³ standard.
**4. Dust-free systems require careful design.**
From inspection to real-world application, proper system design is essential. Dust removal is a complete system, involving not only the equipment itself but also the ductwork resistance and the position and shape of the collection hoods. A well-designed system is crucial for effective performance, especially for high-temperature dust removal from smelting furnaces. Cooling the flue gas from around 500°C down to below 120°C is common, often using natural or forced cooling. This process significantly impacts the dust removal system’s performance. Many companies have saved on initial investment but later faced system failure, proving the importance of proper design.
**5. Comprehensive utilization of waste materials**
Currently, some enterprises have successfully recovered carbon monoxide from silicon carbide smelting exhaust gases. Corundum smelting waste heat is also being utilized. Dust collected during the smelting and granulation process of corundum is expected to yield positive results soon.
**6. Industry-wide environmental challenges**
The loading and unloading conditions for silicon carbide smelting are particularly poor. Achieving clean production is a common concern, and solutions must be economically viable.
**Conclusion:**
The abrasive industry is currently undergoing a rigorous test in the national environmental remediation process. Entrepreneurs are increasingly aware of its importance, and it has become a prerequisite for survival and development. The only solution is to apply mature technologies now, while continuously innovating and improving processes to make abrasive production truly clean, efficient, and intelligent.
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