ABRASION INDEX

The grinding circuit is the largest capital investment of your processing plant. Depending on the grindability of your orebody, abrasion will cause a certain amount of deterioration to the steel media and liners in your circuit. The Abrasion test will allow you to quantify this and design accordingly.

The Bond Abrasion Test determines the Abrasion Index, which is used to determine steel media and liner wear in crushers, rod mills, and ball mills. Bond developed the following correlations based on the wear rate in pounds of metal wear/kWh of energy used in the comminution process.

Wet rod mill Rods lb/kWh = 0.35(Ai – 0.020)0.2

Liners lb/kWh = 0.035(Ai – 0.015)0.3

Wet ball mill Balls lb/kWh = 0.35(Ai – 0.015)0.33

Liners lb/kWh = 0.026(Ai – 0.015)0.3

Dry ball mill Balls lb/kWh = 0.05Ai0.5

Liners lb/kWh = 0.005Ai0.5

Crushers(gyratory, jaw, cone)

Liners lb/kWh = (Ai + 0.22)/11

Roll crushers Roll shell lb/kWh = (0.1Ai)0.667

The abrasion test was developed by Allis-Chalmers* using a method and apparatus used by the Pennsylvania Crusher Division of Bath Iron Works Corp. The equipment consists of a rotating drum into which dry ore samples are placed, with an impact paddle mounted on a centre shaft rotating at a higher speed than the drum. The paddle is made from standard alloy steel hardened to 500 Brinell. The Abrasion Index is determined from the weight loss of the paddle under standard operating conditions.

SGS's results are ranked against our AR MacPherson database so they can be compared against other ores.

Feed Sample Requirements:1.6 kg of minus 3⁄4” plus 1⁄2” ore. This can normally be obtained by taking 5 kg of ore crushed to minus 3⁄4” and screening at 1⁄2”.

SGS's team of experienced engineers will conduct the Abrasion Test in combination with other bench-scale tests and circuit simulation. The use of many methodologies provides you with a bankable solution that is unmatched in its rigor.

FREE SWELLING INDEX

To determine the free swell index of soil as per IS: 2720 (Part XL) – 1977. Free swell or differential free swell, also termed as free swell index, is the increase in volume of soil without any external constraint when subjected to submergence in water. The apparatus used :

i) IS Sieve of size 425µm

ii) Oven

iii) Balance, with an accuracy of 0.01g

iv) Graduated glass cylinder- 2 nos., each of 100ml capacity

strong>Procedure to determine Free Swell Index Of Soili) Take two specimens of 10g each of pulverised soil passing through 425µm IS Sieve and oven-dry.

ii) Pour each soil specimen into a graduated glass cylinder of 100ml capacity.

iii) Pour distilled water in one and kerosene oil in the other cylinder upto 100ml mark.

iv) Remove entrapped air by gently shaking or stirring with a glass rod.

v) Allow the suspension to attain the state of equilibrium (for not less than 24hours).

vi) Final volume of soil in each of the cylinder should be read out.

REPORTING OF RESULTSFree swell index = [Vd – Vk] / Vk x 100%where,Vd = volume of soil specimen read from the graduated cylinder containing distilled water.Vk = volume of soil specimen read from the graduated cylinder containing kerosene.

Free Swell

Index

Degree of

expansiveness

LL PL SL

<20 Low 0.50 0-35%

>17%

20-35 Moderate 40-60%

25-50%

8-18%

35-50 High 50-75%

35-65%

6-12%

>50 Very high >60% >45% <10%