Disk mill

Crushing and grinding uses mechanical force to break larger particles into smaller ones. A variety of tools are used depending on the particle s size and hardness. Large particles are crushed using jaw crushers capable of reducing particles to diameters of a few millimeters. Ball mills, disk mills, and mortars and pestles are used to further reduce particle size. 

Ore samples are analyzed for %w/w Ni. A jaw crusher is used to break the original ore sample into smaller pieces that are then sieved into 5 size fractions. A portion of each fraction is reduced in size using a disk mill and samples taken for analysis by coning and quartering. The effect of particle size on the determination of %w/w Ni is evaluated. 

Mech nic l Impact Mills. The mechanical types include cmshers, hammer mills, pin disk mills, turbine mills, and mills with air classifiers. Impact Crusher. Feed material is introduced through a feed opening onto a rotor moving at between 25 and 50 m/s (Fig. 11). The initial impact by the rotor causes some size reduction, and the material is accelerated up to the speed of the rotor and flung against the impact plates, where further size reduction occurs. It is possible to wear-protect these units quite well, so that abrasive materials can be handled. The final end particle size can be varied by the inclusion of an outlet grid to vary the residence time in the machine. 

Plant material should be added to a disk mill (grain or seed matrices) or a vertical batch processor (all other matrices). Add an equal portion of pelletized dry-ice to the sample (vertical processor only). Macerate the plant sample (or sample -I- dry-ice) until a homogeneous mixture is obtained. Soil samples should be well mixed or... 

Saltpetre (dried at temperatures ranging from 100-110°C if necessary) is milled either in ball mills, using iron balls (Fig. 88), in disk mills (Fig. 89), er in disintegrators. 

Raczynski [9] replaced the beaters for pulping nitrocellulose by disk mills (Fig. 157). A nitrocellulose water suspension flows down from a tank (7) through... 

I Suspend the pigments and talc in the well stirred water and homogenize in a disk mill or in a colloid mill. 

A 500-g sample of this suspension was passed through a disk mill and sprayed under the following conditions ... 

Disinfection efficiency Dis] oimng pressure Disk brakes Disk drives Disk memories Disk mills... 

Pm disk mills - [CARDIOVASCULARAGENTS] (Vol5) - [SIZE REDUCTION] (Vol 22)... 

ATTRITION MILLS. Equipment of this type is used in the process industries to reduce the size of various feeds. Attrition connotes a rubbing action, although this action usually is combined with other forces, including shear and impact. Attrition mills also are referred to as disk mills and normally comprise two vertical disks mounted on horizontal shafts, with adjustable clearance between the vertical disks. In some designs, one vertical disk may be stationary. In other designs, the two vertical disks... 

In industrial and laboratory settings the subdivision process more commonly involves the comminution of large particles or aggregates into smaller sizes, either dry with subsequent dispersion (size reduction to the order of a few pm) or directly in a slurry (size reduction to as small as a few tenths of pm). Examples of comminution machines include agitator ball mills, colloid mills, cutting mills, disk mills, homogenizers, jet mills, mechanical impact mills, ring-roller mills, and roll crushers. 

In Fig. 52 the dependence ds0 =/ (E/pV) is shown for four stirred disk mills of different sizes. The correlation... 

Fig. 52 Correlation d50 (E/pV) for four differently shaped stirred disk mills from [77],...

Figure 10.6. Surfactant demand curves of 70% (weight) dispersions of Ti02 pigments with various levels of alumina treatment. Dispersions were prepared in DIDP plasticizer on a highspeed disk mill. Survactant used was Disperbyk I. Pigment A titania surface, no alumia surface treatment. Pigment B 1.5% alumina surface treatment, minimum viscosity achieved at 2.36% surfactant based on pigment weight. Pigment C 3.0% alumina surface treatment, minimum viscosity at 3.9% surfactant.

Final particle size achieved in a pin disk mill is governed by rotor speed, solids feed rate, and gas flow rate through the mill. Smaller particles can be generated by maximizing rotor tip speed and minimizing both product feed and air flow rate (increasing particle residence time). As equipment scale is increased, maintaining rotor tip speed is one reliable way to achieve milled particle sizes comparable to small-scale results. 

---