Liaoning Xinda Talc Group Co., Ltd. — Cao Xinyu

I. Impacts of Abrasion Value on Three Core Papermaking Equipment

1. Forming Fabrics: Sharply Reduced Service Life and Surging Operation & Maintenance Costs

The forming fabric is a key component in the wet end of paper machines. Made of polyester or polyamide, it keeps rubbing against pulp for a long time. High-abrasion fillers damage the fabric through three effects: abrasive cutting, fatigue spalling and frictional heating. Hard particles plough the fabric wires, repeated impacts generate microcracks, and friction heat accelerates the aging of polymer materials.

Field test case: On a cultural paper machine with a web width of 5.6 m and a running speed of 1200 m/min, after the abrasion value of talc powder rose from 10 mg to 25 mg, the average service life of the forming fabric was shortened from 78 days to 42 days, a decrease of 46%. The cost for each fabric replacement plus production downtime loss was about 180,000 RMB, and the additional annual cost for a single machine exceeded 1.5 million RMB.

2. Paper Cutting Knives: Accelerated Blade Blunting and Degraded Paper Quality

Paper cutting knives perform rotary shearing with micron-level clearances. Hard magnesite particles trapped in paper sheets cause three-body abrasive wear and rapidly blunt the cutting edges.

● When low-grade talc (abrasion value: 35 mg) is adopted, the regrinding cycle of cutting knives is shortened from 7 days to 3 days, and blade consumption is doubled.

● Consequential problems: Blunt cutting edges result in rough paper edges and increased paper dust, which directly impair the quality of subsequent printing processes.

3. Refining Equipment: Lost Energy-saving Effect and Rising Wear and Power Consumption

Talc is a double-edged sword for refining equipment:

●  High-grade talc (purity＞90%): Its lamellar structure provides lubrication and friction reduction, cutting refining power consumption by 5%~8%.

● Low-grade talc: Magnesite particles aggravate the wear of refiner discs and increase frictional resistance. Not only is the energy-saving effect eliminated, but power consumption per ton of paper rises and the service life of refiner discs is shortened.

II. Core Research Conclusions

The fundamental cause of talc abrasion lies in the mineral property difference between talc (Mohs hardness 1, lamellar structure) and magnesite (Mohs hardness 3.5~4.5, rhombic columnar structure), and magnesite is the primary abrasive impurity.

● There is a strong negative correlation between grade and abrasion value: high-grade talc (purity＞90%) has an abrasion value of 6~10 mg; medium-grade talc (75%~90%) ranges from 15 mg to 25 mg; low-grade talc (purity＜75%) measures 30~45 mg. For papermaking use, talc purity is recommended to be no less than 88%, with magnesite content controlled below 8%.

● Abrasion value has a cumulative amplification effect. The service life of forming fabrics declines exponentially with rising abrasion value, and the maintenance cycle of cutting knives shortens linearly. Talc with high impurity content will completely offset its lubrication and energy-saving advantages.

II. Targeted Engineering Application Recommendations

1. For Talc Powder Producers

① Establish a dedicated database covering "grade – magnesite content – abrasion value", and customize products for different papermaking clients according to paper machine speed and fabric material.

② Develop ultra-low-abrasion talc products with abrasion value below 8 mg to fit high-speed and high-end paper machine production scenarios.

2. For Papermaking Enterprises

① Make abrasion value, magnesite content and particle size distribution mandatory incoming inspection indicators for talc powder to control filler quality at the source.

② If low-grade talc is already in use on production lines, increase the number of sand cleaners and optimize the mixing ratio of talc and calcium carbonate to mitigate abrasive damage caused by hard particles.

③ Prioritize high-grade talc with purity ≥88% for high-speed paper machines to balance equipment service life and overall production cost.

IV. Prospect of Future Research Directions

① Further study the friction mechanism of the ternary pulp system consisting of talc, magnesite and fiber, and build an accurate prediction model for abrasion value.

② Explore powder surface modification technology to simultaneously improve the lubricity and low-abrasion performance of talc.

③ Develop machine vision inspection technology to realize rapid on-line detection of talc particle morphology and particle size.