TY - JOUR

T1 - Pumice attrition in an air-jet

AU - Jones, T.J.

AU - Russell, J.K.

AU - Lim, C.J.

AU - Ellis, N.

AU - Grace, J.R.

N1 - This is the author’s version of a work that was accepted for publication in Powder Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Powder Technology, 308, 298-305, 2017 DOI: 10.1016/j.powtec.2016.11.051

PY - 2017/2/15

Y1 - 2017/2/15

N2 - We present the results from a series of jet-attrition experiments performed using a standard ASTM device (ASTMD5757-00) on naturally occurring ash-sized (b 2 mm) pumice, a product of explosive volcanic eruption compris-ing highly porous silicate glass. We investigate the effect of both feed grain size and attrition duration on the pro-duction of fines. We utilize a wet methodology for fines collection to ensure recovery of the total grain sizedistribution for each experimental run. The experiments convert a restricted size range of pumice particles to abimodal population of parent and daughter particles. The bimodal distribution develops even after short(~ 15 min) attrition times. With increased attrition time, the volume of daughter particles increases and themode migrates to finer grain sizes. Jet attrition efficiency depends heavily on the particle size of the feed; ourdata show little attrition for a feed of 500 μm vs. highly efficient attrition for a 250 μm feed. Our rates of attritionfor pumice are extremely high compared to rates recovered from experiments on limestone pellets. Fines pro-duction data are well modeled by:mfinesm0bed¼ 0:291 1−e−0:312t where m0bed is the initial mass of particles in the bed, t is in hours, and the two adjustable coefficients dictate thelong time limiting behaviour (0.291) and the rate at which the limit is reached (−0.312). This functional formprovides more realistic limits in time while preserving a zero intercept and defining a plateau for long residencetimes

AB - We present the results from a series of jet-attrition experiments performed using a standard ASTM device (ASTMD5757-00) on naturally occurring ash-sized (b 2 mm) pumice, a product of explosive volcanic eruption compris-ing highly porous silicate glass. We investigate the effect of both feed grain size and attrition duration on the pro-duction of fines. We utilize a wet methodology for fines collection to ensure recovery of the total grain sizedistribution for each experimental run. The experiments convert a restricted size range of pumice particles to abimodal population of parent and daughter particles. The bimodal distribution develops even after short(~ 15 min) attrition times. With increased attrition time, the volume of daughter particles increases and themode migrates to finer grain sizes. Jet attrition efficiency depends heavily on the particle size of the feed; ourdata show little attrition for a feed of 500 μm vs. highly efficient attrition for a 250 μm feed. Our rates of attritionfor pumice are extremely high compared to rates recovered from experiments on limestone pellets. Fines pro-duction data are well modeled by:mfinesm0bed¼ 0:291 1−e−0:312t where m0bed is the initial mass of particles in the bed, t is in hours, and the two adjustable coefficients dictate thelong time limiting behaviour (0.291) and the rate at which the limit is reached (−0.312). This functional formprovides more realistic limits in time while preserving a zero intercept and defining a plateau for long residencetimes

KW - Pumice

KW - Attrition

KW - Milling

KW - Ash production

KW - Fines production model

KW - ASTM D5757-00

U2 - 10.1016/j.powtec.2016.11.051

DO - 10.1016/j.powtec.2016.11.051

M3 - Journal article

VL - 308

SP - 298

EP - 305

JO - Powder Technology

JF - Powder Technology

SN - 0032-5910

ER -