Carbon Black Grinding Mill and Production Line Process

Carbon black grinding mill is equipment used to grind carbon black into powder. For conventional carbon black powder of 80~400 mesh, an open-circuit Raymond mill is adopted. For ultra-fine carbon black powder above 400 mesh, an open-circuit ultra-fine ring roller mill is selected. If strict requirements are imposed on the particle size distribution of finished products, the combined process of open-circuit pre-grinding plus closed-circuit classification shall be adopted.

What is Carbon Black?

Carbon black is a black powder produced by incomplete combustion or high-temperature pyrolysis of hydrocarbons such as coal, natural gas and heavy oil. Its main component is carbon (content: 90%~99%), with primary particle size ranging from 10 to 100 nm. It features high specific surface area, hydrophobicity, acid and alkali resistance, strong tinting strength, as well as certain electrical and thermal conductivity. Meanwhile, it is a heat-sensitive, flammable and explosive powder. Temperature control and explosion protection must be strictly implemented during grinding.

Notes for Carbon Black Grinding Production Line

Dust Explosion Prevention: Carbon black dust carries explosion risks at a concentration of 50g/m³ (varies by grade). Safety explosion-proof measures must be taken during grinding: first, equip a nitrogen protection system to control oxygen content in the system ≤8%. Install explosion-proof valves and explosion venting discs on key equipment, and adopt anti-static filter bags, explosion-proof motors, explosion-proof electrical cabinets and other explosion-proof electrical components. All pipelines and hoppers are recommended to have reliable grounding (grounding resistance <10Ω), and static eliminators shall be installed at the classifier outlet.

Temperature Control: Heat generated during carbon black grinding tends to cause adhesion, agglomeration and even oxidative spontaneous combustion. Therefore, the grinding chamber temperature must be strictly controlled ≤70℃. For heat-sensitive carbon black grades, cooling gas shall be introduced to stabilize chamber temperature.

Iron Overload Protection: High-intensity magnetic iron remover must be installed before feeding to prevent foreign metal objects from entering the mill. Otherwise, collisions with core components such as grinding rollers and grinding rings may generate sparks and trigger combustion or explosion.

Storage and Transportation: Finished carbon black powder shall be packed in moisture-proof woven bags to avoid compaction and caking. Store in dry, ventilated warehouses away from ignition sources. Mixing storage with oxidants is strictly prohibited. Avoid direct sunlight and violent vibration during transportation. Fire shields shall be equipped on vehicles if necessary.

How to Select Suitable Carbon Black Grinding Mill?

Processing of 80~400 Mesh Carbon Black Powder

For carbon black powder of 80~400 mesh, an open-circuit Raymond mill is commonly used. This process features simple structure and low equipment investment. Carbon black is discharged and collected directly after one-pass grinding, which greatly shortens material residence time inside the grinding chamber and effectively avoids combustion risks caused by over-grinding or temperature rise. It is suitable for conventional industrial fields such as rubber and coatings without strict particle size requirements.

Processing of Ultra-fine Carbon Black Powder Above 400 Mesh

For ultra-fine carbon black powder above 400 mesh, an open-circuit ultra-fine ring roller mill is generally adopted. When strict standards for particle size distribution are required (e.g. high-grade conductive carbon black D50 ≤5μm, pigment carbon black D97 ≤8μm), the open-circuit process lacks return regrinding, resulting in relatively wide particle size distribution and poor uniformity, which fails to meet high-end applications. The combined process of open-circuit pre-grinding + closed-circuit classification is required. The open-circuit ring roller mill pre-processes carbon black to 400~800 mesh first, then cooperates with high-precision turbo air classifier, together with sealed return conveying device to form a closed circulation loop.

Process Flow of Carbon Black Grinding Production Line

Carbon black grinding production lines mostly adopt open-circuit grinding mills. Since raw carbon black particles are fine, crushers are generally not required. After iron removal and screening pretreatment, materials are fed evenly into the open-circuit carbon black grinding mill by feeder for grinding. Materials are discharged rapidly after single grinding and collected as finished powder. The system is equipped with nitrogen inerting protection, explosion venting discs, explosion-proof valves, explosion-proof electrical appliances and spark detection devices. PLC automatic control keeps the grinding chamber temperature stable below 70℃, and oxygen content inside the mill is strictly controlled to prevent spontaneous combustion and dust explosion of carbon black powder at high temperature.

Application Scenarios of Carbon Black Grinding Mill

FAQ about Carbon Black Grinding

Are all carbon black grinding mills open-circuit systems?

No. Any carbon black grinding mill can be configured with open-circuit or closed-circuit system according to production requirements. The selection of these two processes mainly depends on your requirements on finished fineness and particle size distribution.

Can ordinary classifiers be used for the closed-circuit system of carbon black grinding mill?

The closed-circuit system of carbon black grinding mill is usually used for ultra-fine carbon black processing. Ultra-fine carbon black powder tends to adhere, and ordinary classifiers are prone to blockage and metal contamination. High-precision turbo air classifiers must be adopted. High-pressure sealing gas can be introduced if necessary to form a gas barrier and eliminate metal pollution.

How to improve the purity of finished carbon black powder?

Besides installing iron removers, wear of grinding components such as grinding rollers and liners of carbon black grinding mill will produce trace iron debris. Grinding wheels and classifier wheels with full ceramic lining can be used to reduce metal wear and further improve finished product purity.