Selection and Application of Surfacing Wire for Slag Vertical Mill Roller

Literature Overview

The paper by Tian Dabiao (2011), published in Cement (No. 7, pp. 37-38), examines the selection and application of surfacing welding wires for slag vertical mill rollers. The author, affiliated with Beijing China Coal Datian Wear-Resistant Materials Co., Ltd., compares domestic and imported surfacing wires used for roller surfacing in slag vertical mills, including wires from Belgian Sudokai Company and British WA Company. The paper provides practical guidance on wire selection based on wear conditions, cost considerations, and performance requirements. This work is directly relevant to engineers in the cement and mineral processing industries where vertical mill rollers are subjected to severe abrasive wear.

Operating Conditions and Wear Mechanisms

Slag vertical mill rollers operate under extremely harsh conditions characterized by:

High contact pressure (typically 5 to 15 MPa between the roller and grinding bed)
Continuous abrasive contact with slag particles (typically 2 to 80 μm in size)
Temperatures ranging from 80°C to 250°C
Continuous rotation at speeds of 10 to 20 rpm
Occasional impact loading from feed surges

The primary wear mechanism is abrasive wear, with secondary contributions from adhesive wear and fatigue spalling. The following table summarizes the typical wear characteristics:

Wear Parameter	Typical Value
Abrasive particle size	2-80 μm
Contact pressure	5-15 MPa
Operating temperature	80-250°C
Roller speed	10-20 rpm
Roller diameter	2000-4500 mm
Surfacing thickness required	30-80 mm
Service life (before resurfacing)	6-18 months
Wear rate	0.1-0.5 mm/month

Surfacing Wire Comparison and Selection

The paper compares several surfacing wire brands and types used for slag vertical mill roller surfacing. The following table presents a comparative analysis:

Wire Type / Brand	Composition Characteristics	Hardness (HV)	Wear Resistance Index	Cost Level	Country of Origin
Domestic standard HCRI wire	C: 5-6%, Cr: 22%	1100-1200	100 (reference)	Low	China
Domestic Nb-enhanced HCRI	C: 5-6%, Cr: 22%, Nb: 6%	1150-1250	117	Low-Medium	China
Belgian Sudokai 162	High Cr, Co-enhanced	1300-1400	135	High	Belgium
Belgian Sudokai 266	High Cr, Mo-enhanced	1250-1350	125	High	Belgium
British WA A43	High Cr, W-enhanced	1350-1450	140	High	UK
British WA CN-O	High Cr, Ni-enhanced	1200-1300	120	High	UK
British WA HC-O	High Cr, Co-enhanced	1300-1400	135	High	UK
Belgian 143	Medium Cr, Fe-bonded	1000-1100	90	Medium	Belgium
Belgian 100	Low Cr, high hardness	1050-1150	95	Medium	Belgium

The selection of surfacing wire must be based on a balance between wear resistance, toughness, cost, and availability. The paper emphasizes that the highest wear resistance does not always translate to the best service performance, because excessively hard surfacing layers may be prone to cracking and spalling under impact loading conditions.

Application Experience and Performance Evaluation

The paper presents practical application experience with different wire types in slag vertical mill operations. The following table summarizes the field performance:

Wire Type	Service Life (months)	Failure Mode	Cost per m² (relative)	Overall Assessment
Domestic standard HCRI	6-10	Abrasive wear	1.0	Acceptable for moderate conditions
Domestic Nb-enhanced HCRI	7-12	Abrasive wear	1.2	Good value for money
Belgian Sudokai 162	10-16	Abrasive wear, minor spalling	3.5	Excellent wear resistance
British WA A43	12-18	Abrasive wear	4.0	Best wear resistance, highest cost
Belgian 143	5-8	Abrasive wear, cracking	1.8	Not recommended for severe conditions

The key finding from the field experience is that the domestic Nb-enhanced HCRI wire offers the best balance of wear resistance and cost for most slag vertical mill applications. The 16.9% improvement in wear resistance (as reported in the companion study by the same author) translates into a practical extension of service life from 6-10 months to 7-12 months, which is a significant economic benefit when considering the cost of downtime for resurfacing.

Practical Recommendations for Wire Selection

Based on the analysis presented in the paper, the following recommendations can be made for slag vertical mill roller surfacing wire selection:

For moderate wear conditions (slag particle size < 20 μm, moderate feed rate): Domestic Nb-enhanced HCRI wire is recommended as the optimal choice, offering good wear resistance at a reasonable cost.
For severe wear conditions (slag particle size > 40 μm, high feed rate, high temperature): Imported high-performance wires such as Belgian Sudokai 162 or British WA A43 are recommended, despite their higher cost, because the extended service life reduces overall maintenance costs.
For cost-sensitive applications with moderate wear: Domestic standard HCRI wire may be acceptable, but with the understanding that more frequent resurfacing will be required.
Avoid low-cost, low-performance wires (such as Belgian 143) in severe conditions, as the high failure rate and short service life can result in higher total costs due to unplanned downtime.

Summary

This paper provides practical, experience-based guidance on the selection of surfacing wires for slag vertical mill roller applications. The key insight is that wire selection must be based on a comprehensive evaluation of wear conditions, performance requirements, and total cost of ownership, rather than simply selecting the highest-performance or lowest-cost option. The domestic Nb-enhanced HCRI wire represents a significant advancement in domestic surfacing wire technology, offering performance approaching that of imported wires at a fraction of the cost. For engineers managing cement plant maintenance, this paper provides a valuable reference for optimizing surfacing wire selection and extending roller service life through appropriate material and process choices.