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UNIVERSITY ‘ v PERTH, WESTERN AUSTRALIA Examinations  Semester 1, 2007 nit EXM301 MINERAL PROCESSING I
ExamType  Internal & External Time Allowed 3 hours plus 10 minutes reading time INSTRUCTIONS ANSWER ONLY FIVE QUESTIONS EXAMINATION AIDS ALLOWED
Provided by the Universiﬂ GRAPH PAPER (A4 1MM)
GRAPH PAPER (LOGLOG) Provided by the Candidate
CLOSED BOOK EXAMINATION CALCULATOR PERMITTED (NOT GRAPHICS) ANSWER ONLY FIVE QUESTIONS
ALL QUESTIONS CARRY EQUAL MARKS AS INDICATED . How would you determine the size distribution of a SAG mill feed stream that is fed
by a conveyor belt. (5 marks) . Brieﬂy describe the requirements of a sample cutter that may be used to sample a
hydrocyclone underﬂow stream. (5 marks) . The feed to a copper ﬂotation circuit is prepared using a standard SABC
comminution circuit. A 5kg sample of ore is taken by sampling the SAG mill
discharge with a top size of 3mm, so that the assay error is kept to within :h 0.2% Cu
@ 95% level of conﬁdence. What would be the assay error if a sample of 1.0 kg is
taken ﬁom the ﬂotation circuit feed which has a top size of 150p? Note: liberation factor = (liberation size/particle size)'/2 (10 marks) A sample of an ore was batch ground in a laboratory mill. The results of the size
analysis of the ground product are given in the table below. TABLE 1: Sieve Analysis Data Size (microns) Cum.Weight
(%) Passmg
1600 . Evaluate the parameters of the GateGaudin Schuhmann plot of the above product.
(10 marks)
. Hence calculate the amount of ﬁnes below 10 microns in the product. (5 marks)
Determine the sphericity of cubic particle of side 2mm. (5 marks) Describe the characteristic features of a Rod mill, Ball mill and a SAG mill. Highlight any differences in their design and/or operation.
(6 marks) . What are “seats” and explain how you would deal with seats in a comminution
circuit? (4 marks) What are the main beneﬁts of having a circulating load in a grinding circuit
compared to an open circuit operation? (4 marks) . Brieﬂy describe the following: (i) Critical speed of a tumbling mill. (2 marks)
(ii) Grindability of an ore. (2 marks)
(iii) Mill charge. (2 marks) Sketch a typical Grade/Recovery plot that represents a spiral concentrator
performance treating a beach sand that produces a heavy mineral concentrate and a tailing. Give two measures of efﬁciency that can be used to enumerate the efﬁciency of the separation process at a given operating point. Discuss their limitations.
(8 marks) . The feed to a gravity concentrator contains 10% heavy mineral. The concentrate
assays 30% heavy mineral and the tailings assay 1.5% heavy mineral. Determine: (i) The mass % of the feed recovered in the concentrate. (6 marks)
(ii) The separation efﬁciency of the separation. (6 marks)
Describe the working of a spiral classiﬁer or a hydrocyclone. (3 marks) . Explain why the performance curve of a hydrocyclone does not pass through the
origin. Show how it may be modiﬁed to determine a plot that represents the
“machine characteristics” of the hydrocyclone. (8 marks) The reduced performance curve of a jig is shown in Figure 1. If the jig operates at a
cut speciﬁc gravity of 1.6, determine the operating performance curve of the jig.
Also estimate the probable error and the imperfection. (9 marks) Discuss the factors affecting the performance of an industrial screen. (6 marks) . What are washability curves used in gravity concentration circuit design? Sketch
typical curves and illustrate how they are used. (8 marks) Suggest a ﬂow sheet to process a beach sand mineral deposit comprising of the following minerals: Ilmenite, Rutile, Zircon, Monazite and Silica gangue.
(6 marks) 5! Cum Wt. % to Floats Figure 1  05 Reduced Performance curve of Jig 1 00
90
80
7O
6O
50
40
30
20
10 0 T71 _J___ M .L..._ l _ I—
...w... _._._l L—eﬁe a— 0.5 0.6 0.7 0.8 0.9 1 ____'_ 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
ReducedSG ******** END OF PAPER ******** ...
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