Issue 37

Q. Like et alii, Frattura ed Integrità Strutturale, 37 (2016) 342-351; DOI: 10.3221/IGF-ESIS.37.45

Thermal conductivity (w/ m )

Specific heat capacity (J/k g ° C)

25 ° C

100 ° C

227 ° C

25 ° C

227 ° C

727 ° C

Calcite Galena

4.02 2.76

3.01 2.45

2.55 1.92

819 208

1051

1238

215 234 Table 4 : Thermal conductivity and specific heat capacity in different temperatures. 100 ° C 200 ° C 400 ° C 600 ° C Calcite 1.31 1.58 2.01 2.4 Galena 6.12 6.10 6.32 --

Table 5 :Thermal expansion coefficient in different temperatures (10 −5 ).

C ALCULATION RESULTS AND ANALYSIS

M

Analysis under low power density

icrocrack distributions under different irradiation times (0.5 and 1.5 s) when P d =1×10 9 W/m 3 are shown in Figs. 3 and 4. The total number of microcracks, number of microcracks in galena, number of microcracks in quartz, and boundary damage rate are given. Viewed as stress types, different shapes of minerals develop many tensile cracks and few shear cracks. The shape of galena will not influence crack types. Cracks can be divided into three types according to position distribution: 1) Diffused cracks, which develop in calcite and point to the center, which can break gangue. 2) Calcite-galena interface cracks, which can separate galena from calcite. 3) Cracks in galena, which are extensions of the first crack in calcite into galena during early irradiation. The first two types are good for mineral dissociation while the third type breaks minerals. Excessive cracks in galena are disadvantageous for mineral dissociation.

Figure 3 : Microcrack distributions in different shapes of minerals (t = 0.5 s)

Figure 4 : Relation curves of microcrack number and irradiation time (t = 1.5 s)

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