-
Notifications
You must be signed in to change notification settings - Fork 3
/
Copy path3_BowRiver.html
189 lines (161 loc) · 10.7 KB
/
3_BowRiver.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<!--
Design by Free CSS Templates
http://www.freecsstemplates.org
Released for free under a Creative Commons Attribution 2.5 License
-->
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
<title>Diamonds and Diamond Exploration
</title>
<meta name="keywords" content="" />
<meta name="description" content="" />
<link href="default.css" rel="stylesheet" type="text/css" />
</head>
<body>
<div id="header">
<div id="logo">
<h1><a href="#">Grant's Diamond Pages</a></h1>
</div>
<div id="menu">
<ul>
<li class="active"><a href="index.html" title="">Homepage</a></li>
<li><a href="About.html" title="">About Me</a></li>
<li><a href="QGIS.html" title="">QGIS</a></li>
<li><a href="Astro.html" title="">Astronomy</a></li>
<li><a href="Diamonds.html" title="">Diamond Exploration</a></li>
<li><a href="Impacts.html" title="">Meteorites and Impacts</a></li>
<li><a href="Bibliography.html" title="">Bibliography</a></li>
</ul>
</div>
<div id="AboutMeText" style="text-align:center;height:400px;margin:auto">
<br>
<div>
<STYLE type="text/css">
p { text-align: center}
</Style>
<br>
<h1>Bow River Alluvial Diamond Mine</h1>
<br>
<p>The diamonds recovered from the mining operations were valued at about US$25 per carat and included the
rare pink diamonds that have made the Argyle mine famous.</p>
<img src="images/BowRiver/BowRiverDiamonds.jpg">
<br>
</p> The photo above is from Fazakerley (1990).</p>
<p>The Bow River alluvial diamond deposit occurs on the lower reaches of
Limestone Creek, about 20 km north east of the Argyle diamond mine. The
deposit was discovered by Gem Exploration and Minerals in the early 1980's and
mined by Poseidon/Freeport and Normandy from 1988 until late 1995. The mine was known
as the Normandy Bow River Diamond Mine (NBRDM) after the Normandy take-over of
Freeport. The plant was placed under "care and maintenance" at the end of
mining in late 1995. Astro Mining NL (Astro) purchased the tenements and
infrastructure in late 1998 and undertook a review of the alluvial potential of
the area. </p>
<p>Unfortunately insufficient resources were located to support a viable mining operation and the plant and infrastructure were rehabilitated a few years later. There remains about 1 million tonnes at a low diamond grade in the area but this area is regularly flooded each wet season with the rise and fall of Lake Argyle. Astro Mining carried out an extensive review of the data obtained from NBRDM searching for additional alluvial resources, as well as flying some detailed aeromagnetic surveys in the area seeking possible lamproite occurrences. Unfortunately none were found. Astro were also involved with joint ventures in the area with Conquest Mining testing the alluvial gravels of the Bow River to the south and east of the Argyle mine and alluvial gravels adjacent to the mining leases of the lower reaches of Smoke Creek.</p>
<br>
<h2>Geology</h2>
<br>
<p>The diamondiferous gravels of the Bow River alluvial deposit lie immediately
north of Limestone Creek, some 20 km downstream from the
<a href="2_Argyle.html">Argyle</a> pipe. The area of the
alluvial deposits forms part of a low lying broad alluvial plain covered by
superficial sand, silt, gravel and black soil (Biggs and Garlick 1987). Five diamondiferous gravel horizons were identified and
two horizons, the T1 and T2 gravels, were the main focus of mining.
Freeport defined a proven in-situ geological reserve of 1.434 mt at 0.524 ct/t
for the T1 gravels and 9.945 mt at 0.383 ct/t for the T2 gravels. The mine produced some 7 million carats from the mining of about 24 million
tonnes of gravels.</p>
<br>
<img src="images/BowRiver/BowProj_B&G_FigBR3_620px.jpg" />
<br>
<p>The image above is from the prospectus by Biggs and Garlick(1987) and shows the distribution of gravels and a cross section through the deposit. The economically mineralised gravels occurred as
exposed surface gravels (T1) and under a black soil plain (T2) to the north of
the current location of Limestone Creek. The T1 gravels are ferruginous in
nature and are probably equivalent to the B Terrace gravels at the Argyle mine.
The T1 gravels range in thickness from 0.04 to 1.1 m thick and were best exposed
on isolated small hills. The T2 gravels are concealed beneath 0.6 to 5.7 m
of black soil and range in thickness from 1.1 to 2.9 m. The gravels
consist of cobble and boulders of up to 200 mm in diameter. The T2 gravels
are probably equivalent to the C Terrace gravels of Argyle. Younger T3 and
T4 gravel horizons cross cut the T2 gravels and are reworked gravels from the T2
gravels. The T5 gravels form the present day creeks. </p>
<p>The deposit was evaluated by pitting for geology followed by bulk sampling for diamond grade. This process
was also used during the mining stage for mine planning. The images below shows the geological pits (small) with the larger pits excavated for grade determination.</p>
<p>The majority of the images below have been scanned from colour slides taken from the NBRDM offices before the offices were rehabilitated and were presumable taken by NBRDM staff during operations about 1992.</p>
<img src="images/BowRiver/PitMapping.jpg" target="_blank">
<p style="text-align:center">Geologist mapping pits for geology.</p>
<img src="images/BowRiver/MiningPits1.jpg" target="_blank">
<p style="text-align:center">Alluvial gravels exposed in pit.</p>
<img src="images/BowRiver/MiningPits2.jpg" target="_blank">
<p style="text-align:center">Large pit showing alluvial gravels.</p>
<img src="images/BowRiver/MiningPits3.jpg" target="_blank">
<p style="text-align:center">Bulk sample pit.</p>
<img src="images/BowRiver/MiningPits4.jpg" target="_blank">
<p style="text-align:center">Exposed alluvial gravels.</p>
<img src="images/BowRiver/MiningPits5.jpg" target="_blank">
<p style="text-align:center">Alluvial gravels in pit.</p>
<img src="images/BowRiver/MiningPits6.jpg" target="_blank">
<p style="text-align:center">Large excavation exposing alluvial gravels.</p>
<img src="images/BowRiver/MiningPits7.jpg" target="_blank">
<p style="text-align:center">Bulk sample pit.</p>
<img src="images/BowRiver/BRDM_ResourcePits.jpg" target="_blank">
<p style="text-align:center">General view of the area showing small pits for geology and larger pits for grade determination.</p>
<h2><!--mstheme--><font color="#006666">Mining<!--mstheme--></font></h2>
<p>Mining was carried out by scraper to remove the overburden and hydraulic
excavators to mine the gravel
horizon and load into dump trucks. The image on the left shows the mining
operation. </p>
<img src="images/BowRiver/Mining8.jpg" target="_blank">
<p style="text-align:center">Overburden stripping by scraper.</p>
<img src="images/BowRiver/Mining4.jpg" target="_blank">
<p style="text-align:center">Mining of alluvial gravels using hydraulic excavator.</p>
<img src="images/BowRiver/Mining5.jpg" target="_blank">
<p style="text-align:center">Pitting of gravels below overburden layer.</p>
<img src="images/BowRiver/Mining1.jpg" target="_blank">
<p style="text-align:center">Aerial view of mining.</p>
<img src="images/BowRiver/Mining2.jpg" target="_blank">
<p style="text-align:center">Aerial view showing excavator and truck mining alluvial gravel layer.</p>
<img src="images/BowRiver/Mining3.jpg" target="_blank">
<p style="text-align:center">Aerial view of mining.</p>
<img src="images/BowRiver/BRDM_Mining2.jpg" target="_blank">
<p style="text-align:center">Mining area showing batter of overburden behind truck and calcreted bedrock in the left of the photo.</p>
<img src="images/BowRiver/Mining6.jpg" target="_blank">
<p style="text-align:center">View of mined block before infilling and rehabilitiation.</p>
<img src="images/BowRiver/Mining9.jpg" target="_blank">
<p style="text-align:center">Overburden stripping.</p>
<h2><!--mstheme--><font color="#006666">Processing<!--mstheme--></font></h2>
<p>The process plant comprised a fairly typical scrubbing, screening and DMS separation plant with magnetic
separation and X-ray sorting to process the concentrate. The product from the X-ray machine was hand sorted, then cleaned for export. The plant had
a capacity of about 3.7 million tpa and recovered diamonds from 19 to 1.5 mm in size. </p>
<img src="images/BowRiver/BowRiverPlant.jpg" target="_blank">
<p style="text-align:center">Overview of plant looking towards the Argyle mine the from waste dump.</p>
<img src="images/BowRiver/Plant_FeedBin.jpg" target="_blank">
<p style="text-align:center">Feed bin area.</p>
<img src="images/BowRiver/Plant_FeedingPlant.jpg" target="_blank">
<p style="text-align:center">Loading the feed to the plant.</p>
<img src="images/BowRiver/Plant_Feed.jpg" target="_blank">
<p style="text-align:center">Loader digging feed for plant.</p>
<img src="images/BowRiver/Plant_OverView.jpg" target="_blank">
<p style="text-align:center">View of the processing plant.</p>
<img src="images/BowRiver/Plant_Scrubbing_Screening.jpg" target="_blank">
<p style="text-align:center">Scrubbing and screening section.</p>
<img src="images/BowRiver/Plant_Scrubbing_Screening1.jpg" target="_blank">
<p style="text-align:center">Scrubbing and screening plant.</p>
<img src="images/BowRiver/Plant_Screening.jpg" target="_blank">
<p style="text-align:center">Screening operations.</p>
<img src="images/BowRiver/Plant_Screening1.jpg" target="_blank">
<p style="text-align:center">Screening operations.</p>
<img src="images/BowRiver/Plant_HMS.jpg" target="_blank">
<p style="text-align:center">HMS cyclones.</p>
<img src="images/BowRiver/Plant_RecoveryPlantFeedConveyor.jpg" target="_blank">
<p style="text-align:center">Conveyor to the concentrate processing area of the plant.</p>
<img src="images/BowRiver/Plant_ConcentrateProcessingBuilding.jpg" target="_blank">
<p style="text-align:center">HMS concentrate processing area.</p>
<img src="images/BowRiver/Plant_HMSFeedConveyor.jpg" target="_blank">
<p style="text-align:center">HMS concentrate conveyor.</p>
<img src="images/BowRiver/Plant_PowerHouse_Workshops.jpg" target="_blank">
<p style="text-align:center">Workshop areas.</p>
<img src="images/BowRiver/Camp.jpg" target="_blank">
<p style="text-align:center">Mine camp.</p>
</body>
</html>