Document x1NLYqk8QgZ6LjqyJQr55Brdy
THE CONSOLIDATION OF FOOTWALL DUST IN UNDERGROUND INTAKE HAULAGES AND TRAVELLING WAYS IN GOLD MINES
by J.H. Quilliam* and A.J.P. Van Wyk*
INTRODUCTION
Vehicular and pedestrian traffic in mine haulages leading from downcast shafts, in which air velocities are high, raises much dust if the haulage footwalls are not adequately consolidated.
The use of water for allaying dust in haulages is not entirely satisfactory; firstly because the practice is in opposition to the need to keep the relative humidity of the air as low as possible and, secondly, because of the frequency with which water must be applied if its use is to be effective. Waste engine oil 1 which has been used for this purpose with advantage is no longer freely available as previously, and a substitute has accordingly been sought.
MULREX 925, marketed by the Mobil Oil Company has been identified as a suitable substitute for waste engine oil for allaying dust in haulages. The material is water soluble and can be applied by spraying, and is readily available.
TEST PROCEDURES
(i) Site; Tests were conducted in a relatively newly-developed haulage, not previously treated with oil, not currently carrying any traffic, and not being watered. The footwall was dry with a thick layer of unconsolidated fine dust and "gravel" on the footwall. The air velocity in the haulage was 4 m/s. (ii) Method: The dust created by four men walking through the section of the haulage, or sweeping the footwall of the test section, was measured before and after treatment of the footwall. Long-period thermal precipitator or gravimetric sampling was precluded by the short duration of tests, and assess ment of dust concentrations in the intake air to and the return air from the test section were, therefore, based on konimeter sampling.
Various concentrations of MULREX 925 solutions were applied to the footwall test sections on the areas between the locomotive tracks and the travelling way next to the tracks. The area between the tracks and the drains was not treated.
RESULTS The results of tests covering the range of concentrations of MULREX 925 are given in the following
tables.
Site No. 1
MULREX used per treatment
60/
Water used
600/
Concn. MULREX
10% (1:10)
Area treated (m2)
36 X 2,5 = 90
Cost of MULREX per treatment at 32c//
R19,20
Cost/m2 per
treatment
21c
* Dust Division, Research Services, Chamber of Mines Research Organisation. Journal of the Mine Ventilation Society of South Africa, December, 1977
245
The Consolidation of Footwall Dust in Underground Intake Haulages and Travelling Ways in Gold Mines.
TEST
KONIMETER DUST CONCNS (p/ml)
Intake
No. of Samples
Ave Concn
Return
No. of Samples
Ave Concn
Dust prod, by diff.
1 87 53 99 1 318
2
52
85 57
123
3 31
69 67
271
4 25 113 42 144
5 20 64 20
72
6 31
54 38
82
7 30 100 34 119
8 21
84 20
97
9 25
54 25
187
10 29
63 30
86
11
45
58 46
128
12 40
79 40
122
*Footwall being swept by four workers using bristle brooms.
1 265 38
202 31 8 28 19 13
133 23 70* 43*
Site No. 2
MULREX used per treatment
Waterused
Concn. MULREX
Area treated (nr2)
7,5/
300/
2,5% (1:40) 15 X 2,5 = 37,5
TEST
KONIMETER DUST CONCNS (p/ml)
Intake
No. of Samples
Ave Concn
Return
No. of Samples
Ave Concn
Dust prod, by diff.
1 20 139 20 971 2 20 107 28 150 3 30 43 37 88 4 21 152 20 212 5 22 66 18 210 6 34 74 30 226 7 40 178 41 723 8 42 41 42 231 9 41 67 42 297
832 43 45 60 144
152 545* 190* 230*
*FootwaIl being swept by four workers using bristle brooms.
Site No. 3
MULREX used per treatment
Water used
Concn. MULREX
Area treated (m2)
3,3/
198/
1,7% (1:60)
25
REMARKS
No treatment 12 days after 1st treatment 19............................. 38 days after 2nd treatment 46............................. 54............................. 62............................. 70............................. 78............................. 87.............................
137............................. 160.............................
Cost of MULREX per treatment at 32c//
R2,40
Cost/m2 per
treatment
6,5 c
REMARKS
Before treatment
8 days after 1st treatment
8 days after 2nd treatment
16.............................
24.............................
30 " " "
"
54......................................
88......................................
no......................................
Cost of MULREX per treatment at 32c//
R 1,06
Cost/m2 per
treatment
4,2c
246 Journal of the Mine Ventilation Society of South Africa, December, 1977
The Consolidation of Footwall Dust in Underground Intake Haulages and Travelling Ways in Gold Mines.
TEST
1 2 3 4 5
KONIMETER DUST CONCNS (p/ml)
Intake
No. of Samples
Ave Concn
Return
No. of Samples
Ave Concn
Dust prod, by diff.
30 105 39 1 224
33
40 30
202
36 104 35
181
40
72 40
223
38
87 41
214
1 119 162 77 151 126
REMARKS
Before treatment
34 days after 1st treatment
41 ,, ,,
,,
49............................ 56............................
COMPARISON OF COSTS
Concn. of MULREX in water
1:10 (10%)
1:40 (2,5%) 1:60 (1,6%)
Cost/m2
21c 6,5c 4,2c
CONCLUSIONS The effectiveness of MULREX 925 in consolidating haulage footwall dust has been demonstrated.
The effectiveness of the solution is clearly dependent on the concentrations used. It is possible that the interval between applications may be extended significantly by the use of more concentrated solutions, but this possibility has not been examined.
The results given in this report should be construed as a guide to the application of MULREX 925. Mines wishing to use this material should conduct appropriate tests to ensure that application is matched to the conditions of the particular haulages concerned.
REFERENCE
1. VISSER, B.C. The use of oil for footwall consolidation in dry downcast airways. J. Mine Vent. Soc. S.Afr., Vol. 16, No. 6, June, 1963, pp. 98.
AC KNO WLEDGEMENT
The permission of the Chamber of Mines of S.A. to publish this note is kindly acknowledged.
ERRATA
In the paper "Note on the Inter-Action between Barometric Pressure and Methane Issuing from Fissures" by H.M.W. Eschenburg which was published in the October, 1977 Journal there was a printing error in the last sentence. This should read.
"It is evident that the barometric pressure graph forms a mirror image of the methane level graph, that is when the barometric pressure drops, the methane level increases and when the barometric pressure increases, the methane levels decrease".
Apologies are made for any inconvenience caused.
Editor
Journal of the Mine Ventilation Society of South Africa, December, 1977
247