Recent developments in spiral separator design include 3 mineral models; EP, HC and MG7S; and one coal model, the LD7C.

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1 Specific Spiral Developments Recent developments in spiral separator design include 3 mineral models; EP, HC and MG7S; and one coal model, the LD7C. The EP (Enhanced Performance) Spiral For some time (approximately 12 years?) the MG4 (Medium Grade 4) model spiral separator and its derivatives (MG4A, MG4B, MG4C, MG5) have been the most popular choice in rougher and scavenger spiral applications. The MG4 models are 7-turn units with a diameter of 630(?) mm and all share a common trough design. A single auxiliary concentrate splitter is located 4 turns from the top. Standard units come fitted with 2 repulpers. The function of repulpers is to capture and divert a portion of water from the high velocity tailing stream and introduce it to the relatively sluggish middling stream in order to fluidise the particle bed and re-initiate separation mechanisms. Improvements in separation efficiency, from the application of these devises, have been consistently measured in development work over the past 4 years. The EP (Enhanced Performance) model spiral separator has been developed to supersede (in most applications) the MG4 family of spiral models. The EP model incorporates similar profile and pitch features (to the MG4) that have been refined, blended and compressed into only 6 turns using specifically developed software for design and prototype cutting. The current EP trough design is the fourth in a series of prototypes that have been performance tested and refined. The MG4 trough design originated from the traditional method of manually sweeping individual, half-turn intervals. It can be appreciated, that producing a mould for a new model, using the traditional method, was a formidable undertaking. Computer assisted prototyping is a significant advance. Physical features that distinguish the EP model from its predecessors include; reduced overall height (6 turns compared with 7), reduced turbulent zones, reduced wall height for better access in triple-start assemblies, a deeper concentrate channel and improved edge-roll for containing splash and high volumetric flows. Additionally, the EP model is fitted with 2 new generation repulpers, of a patented design, that ride on top of the stream and therefore dynamically self-adjust to variations in volumetric flowrate. Previous repulpers were fixed. If the flowrate increased beyond a certain level, their action became too violent and therefore counterproductive. On the other hand, their effective contribution was negated altogether if the flowrate dropped to a level below their influence. The new design allows the repulper to make a more optimal contribution over a wider range of operating conditions. As well as being self-adjusting, the new repulper has an improved action with a well-distributed, fan-like spray. No lids are necessary as the new repulpers are splash free. The metallurgical performance of the EP model spiral separator has been measured and benchmarked against MG4 and other rougher models. Performance testing so far has focused on a variety of mineral sand feed types from various parts of the world. In 6 out of 7 different feed types tested, the EP demonstrated a superior performance.

2 Performance Data The data plotted below (in the form of 2 recovery curves) pertain to testwork conducted on an American mineral sand sample. A development model EP spiral was tested along side an MG4C model spiral. The data (from a series of 4 tests) show a clear performance advantage to the EP model. Rougher Spiral Development HM Recovery % EP Spiral EP, Test, 2.10 t/h, 31.4 % sol EP, Test 51, 2.11 t/h, 31.6 % sol MG4 Spiral MG4C, Test 48, 2.11 t/h, 29.0 % sol MG4C, Test 46, 1. t/h, 28.0 % sol Mass take % A series of 6 tests was conducted on a sample of mineral sand from South Africa. The tests covered a range of 3 different feed rate loadings. Recovery curves were plotted for individual tests and respective HM recovery values were interpolated at 15% yield. The summarised data plotted below indicate that, at 15% yield to concentrate, the EP spiral recovered 3 to 5% more HM than the MG4 over a range of feed rates.

3 Recovery (at 15% yield) vs Feed Rate (t/h) r15 EP Spiral MG4B The chart below displays plots of similar data for the same 3 tests using recovery at 30% yield. At this yield, the improvement in HM recovery to the EP spiral has increased to between 5 and 7%. Recovery (at 30% yield) vs Feed Rate (t/h) r30 EP Spiral MG4B

4 High Capacity Spirals As the metallurgical performance on spirals has been refined, and advances have been made in progressively smaller increments, attention has turned towards other attributes, particularly feed capacity or throughput. The aim has been to increase the throughput per unit of space occupied, for a given metallurgical performance. The most obvious application is in rougher type spirals as it is the rougher stage that occupies the greatest space in a spiral plant. Reduction in space results in physically smaller plants and lower capital costs. Higher capacities on individual units also lead to advantages in simplified distribution and laundering systems. A high capacity mineral spiral (the MG2 model) was developed in 19##. The MG2 is a 6-turn unit, almost 1 meter in diameter compared with approximately 0.6m for most conventional mineral spirals. At this diameter, the geometry of the spiral is such that 4 troughs can readily be wound together on a single column producing a quad-start. It is normal for most mineral spirals to be assembled as triple-starts. The MG2 quad-start configuration represents a 33% increase in available trough space for a given footprint. The MG2 model spiral separator was found to be successful on certain feed types offering significant space (and therefore cost) savings. For this reason it has found particular favour in certain mineral sand and tantalum operations. Its metallurgical performance proved to be sensitive to feed characteristics and it was found to be less versatile than the widely accepted MG4 in most rougher applications. Responding to market demand, R&D effort focused on development of a high capacity unit that was more versatile and physically smaller than the MG2 model. A 6-turn, high capacity prototype (HCP) was developed with a diameter of 8mm. This diameter was designated as the smallest that would still allow quad-start assembly within the anticipated geometric design envelope of cross trough slopes, down-trough slopes and profile variations. Second and third derivatives of the HCP were produced, each with different pitch, slope and profile characteristics. The three models are now referred to as HC1, HC2 and HC3. Features that all three have in common include the number of turns (i.e. 6), 8mm diameter, a single auxiliary splitter and 2 new generation repulpers. Each of the 3 HC models demonstrates individual performance characteristics and therefore each design has been retained to meet particular needs in the field. The HC1 is a spiral model aimed at general application with a tolerance of variation in feed characteristics such as mineral assemblage and particle size distribution. The design of the HC2 was initiated after it was observed that the slurry velocity on the HC1 was faster than predicted. The pitch and profile design of the HC2 was targeted towards gentler flow behaviour. As a result the HC2 has been found to be well suited to finer sized and more difficult to separate feed, albeit at lower loadings. The HC3 model was a more experimental model that proved to be capable of very high volumetric and solids feedrate loadings. Higher slurry velocities mean that at low to normal operating loads (4 to 6 t/h/start for HC spirals), the separation efficiency is not as high as its HC1 and HC2 counterparts. However, as the feedrate increases to very high levels (7 to 10 t/h/start), the separation efficiency of the HC3 holds ground somewhat while the HC1 and HC2 fall away. Performance data A comprehensive test program was conducted, comprising some 53 tests, on a Western Australian mineral sand in which the development HCP spiral was tested against the MG4C model spiral the and the MG2 model spiral. The HCP was tested with several repulper configurations. The most successful configuration was the unmodified trough fitted with two repulpers.

5 The following chart provides a summary of the results on the basis of HM analysis. MG4C compared to HCP (with repulpers) Recovery Performance HM Recovery MG4C 30% mass take 40 MG4C 20% mass take MG4C 10% mass take 30 HCP repulp. 30% mass take 20 HCP repulp. 20% mass take 10 HCP repulp. 10% mass take It is clear that the HCP achieved equivalent recovery performance at feed rates that are very close to double those of the MG4C. For example, the chart shows that each spiral achieved % HM recovery at a 30% mass take to concentrate. This occurred on the MG4C spiral at approximately 2 t/h per start (using the best results) and 4 t/h/start on the HCP. The following chart compares the HCP (with and without repulpers) to the MG2 and the MG4C.

6 Performance Comparison MG4C, HCP, MG2 HM Recovery at 30% mass take HM Recovery MG2 MG4C HCP 2 repulpers HCP no repulpers Note that the MG4C and the MG2 were each fitted with 2 repulpers as standard practice. It is evident that, on this feed type, the HCP shows a clearly superior performance to the MG2. A series of 16 tests was conducted on a different Western Australian mineral sand. Eight (8) of the tests were selected for XRF analysis to assess separation performance on the basis of TiO 2 and ZrO 2 Results are summarised below in table x.x. Table x.x Summary of Test Results Test Spiral Feed rate Pulp Density TiO 2 ZrO 2 Number Model t/h % solids r15 r20 max. Eff'y calc grd r15 r30 Max. Eff'y calc grd 2 MG4B MG4B MG4B MG4B HCP HCP HCP HCP HCP ave' 2.56 ave' 0.10 Performance comparisons were made in terms of recovery values at given yields and also maximum separation efficiency values. Figures x.x and x.x below contain charts showing feed rate (t/h) versus performance for MG4B and HCP model spirals. The charts pertain to TiO 2 and ZrO 2 respectively.

7 TiO 2 Separation Performance Recovery Performance MG4B r20 MG4B r15 MG4B Max. eff'y HCP r20 HCP r15 HCP Max. eff'y Figure x.x Performance (TiO 2 ) versus Feed Rate ZrO 2 Separation Performance Recovery Performance MG4B r30 MG4B r15 MG4B Max. eff 'y HCP r30 HCP r15 HCP Max. eff'y Figure x.x Performance (ZrO 2 ) versus Feed Rate The data plotted in figure x.x, pertaining to TiO 2, indicated encouraging performance of the HCP. At 20% yield, the MG4B achieved 93% TiO 2 recovery, at a feed rate of 2.0 t/h. For the same yield, the HCP achieved equivalent performance, at double the feed rate, i.e 4.0 t/h. However, the data indicated that the HCP had greater tolerance of a % increase in feed rate. An increase from 2 to 3 t/h on the MG4B resulted in a recovery decrease from 93 to 88%. An increase from 4 to 6 t/h on the HCP resulted in a recovery decrease from 93 to approximately %.

8 It is noted that a greater degree of scatter occurred with the HCP results and that test 18 may have been an outlier. The removal of test 18 from the data set had a marginal impact on the fitted lines reducing the fitted r20 line by approximately 1% as shown in figure x.x below. TiO 2 Separation Performance Recovery Performance MG4B r20 MG4B r15 MG4B Max. eff 'y HCP r20 HCP r15 HCP Max. eff'y Figure x.x Test 18 removed from data set. The data indicate lower maximum efficiencies for the HCP. This is attributed to a generally sharper inflection on the MG4B recovery curves. However, in rougher applications, recovery is the overriding performance criteria. It was concluded that for this material, the HCP was found to achieve similar performance in terms of TiO 2 recovery, to the MG4B, at feed rates of at least double those of the MG4B. A series of tests was conducted on an Australian East Coast mineral sand sample in which the performance of an HC2, an HC3 and a standard diameter rougher spiral were compared. Recovery Performance on Australian East Coast Feed HM Recovery % Standard Rghr sp R30 HCP3. 2xRepulpers r30 HCP2. 2xRepulpers r

9 The data show favourable performance to the gentler HC2 over the range of 4 to 7 t/h/start. In fact, the HC2 reaches the limit of its feed capacity at 8 t/h. The curves cross at 7 t/h and from 7 to 10 t/h the HC3 is superior. Compound Coal Spiral The LD7C model coal spiral separator represents a development that essentially incorporates 2 stages in 1. Typical coal spirals consist of 3 to 4 turns with a diameter of approximately 9(?) mm. The LD7C consists of 2 modules. The first module constitutes a 3-turn rougher producing a rejectable refuse stream and a primary product that is introduced to a 4-turn cleaner module immediately below it. It has been well established that 2 stages are more efficient that a single stage and the LD7C offers a 2-stage option without the requirement of an additional pump, sump and associated distribution and laundering system. Coal spirals are distinguished from mineral spirals by reduced slurry velocities. This is important as most of the active separating mechanisms rely on contact with the trough surface and therefore rely, in turn, on slurry flows being gentle enough to allow particle settling. Since the sg of a coal particle is so low as to approach that of water, laminar fluid behaviour is even more important on coal spirals than on mineral spirals. It was therefore considered important to interrupt and arrest the flow at the end of the 3-turn rougher stage, rather than let it continue at terminal velocity for the full 7 turns. The feed box of the 4-turn cleaner stage dissipates the energy and allows the feed to re-accelerate over the 4 turns. The flexibility of the design is such that 3-turn rougher modules can be retrofitted to existing banks of spirals to transform single spiral stages into 2-stage circuits. An extra 1.7 (?) meters of headroom is required and the distributor has to be raised but this is usually readily accommodated in applications where the improved yield will provide a quick payback for the plant modifications. Typical performance data: Rougher Stage d range 1. to 2.20 Combined compound d range 1. to 1. Combined Compound d Range for clean Coal with middlings recycling 1. to 1. Rougher stage Ep range 0.17 to 0.20 Combined compound Ep range for clean coal product 0.12 to 0.17 Combined compound Ep range for clean coal with middlings recycling 0.10 to 0.15 The Hybrid Medium Grade/Fine Mineral Spiral Responding to a specific user request, a hybrid spiral (the MG7S) was developed to meet a duty that called for equivalent metallurgical performance to the MG4 while providing flow behaviour at the discharge whereby the tailing could be split into 2 distinct streams. (1) A high-sand / low-water stream and (2) a high-water / low-sand stream. This meant that the slurry had to be slowed and steadied to allow settling of sand particles, while still maintaining transport of the material. The criterion was to produce a sand tailing of >% solids pulp density and a water tailing of <5% solids pulp density. The MG7S model spiral separator is a hybrid with the upper turns similar to that of the MG4 model. A transition occurs and the lower turns blend into a similar design to that of the FM1 (fine mineral) model spiral.