WO2007046050A1 - Spiral separator and control system - Google Patents
Spiral separator and control system Download PDFInfo
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- WO2007046050A1 WO2007046050A1 PCT/IB2006/053789 IB2006053789W WO2007046050A1 WO 2007046050 A1 WO2007046050 A1 WO 2007046050A1 IB 2006053789 W IB2006053789 W IB 2006053789W WO 2007046050 A1 WO2007046050 A1 WO 2007046050A1
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- control arrangement
- slurry stream
- feed
- slurry
- parameter
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
- B03B5/62—Washing granular, powdered or lumpy materials; Wet separating by hydraulic classifiers, e.g. of launder, tank, spiral or helical chute concentrator type
- B03B5/626—Helical separators
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B13/00—Control arrangements specially adapted for wet-separating apparatus or for dressing plant, using physical effects
Definitions
- a control arrangement for controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, comprising
- adjustment means for adjusting at least one feed slurry stream parameter in response to the result of the calculation from the calculation means.
- the calculation means may utilise a mathematical model for calculating how the at least one slurry parameter may be adjusted.
- the mathematical model may include a function of the form:
- Rv f is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function ⁇ is a function of a plurality of slurry stream parameters.
- the function for ⁇ may have been predetermined by means of polynomial regression by means of experimental analysis.
- the apparatus for changing the particle size distribution may be a cyclone.
- the fluid addition means may comprise apparatus for the addition of fluid to the system, the fluid being any one of the group consisting of dilution water, slurry and any combination thereof.
- the control arrangement may operate by means of a feedback loop. Thw control arrangemnet ay utilise a predictive model in a feedforward loop.
- the control arrangement may operate by means of a feedforward loop.
- a plurality of feed stream parameters may be adjusted in response to the measurement of the measured slurry stream parameter.
- the feed slurry characteristic may be altered by the addition of fluid.
- the adjustment of the feed slurry characteristic may be accomplished automatically by means of a looped feedforward control system.
- a control arrangement for controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process comprising
- adjustment means for adjusting at least one feed slurry stream parameter in accordance with a predetermined mathematical model of the separation process in order to optimize the efficiency of the separation process.
- the measuring means may measure a slurry parameter or a change in a slurry parameter. At least one of the measured slurry parameters may be the slurry feed grade.
- the adjusted slurry stream parameter may not be the same slurry parameter that was measured.
- a slurry parameter directly related to the efficiency of the separation process may be the optical characteristics of the separated slurry bands.
- R R" where R Vf is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function ⁇ is a function of a plurality of slurry stream parameters.
- the function for ⁇ may be predetermined.
- the measuring means may measure a slurry stream parameter in the feed slurry stream.
- the optical characteristic parameter may be the optical characteristics of the slurry stream after being radiated by various frequencies of radiation, and when monitored through devices sensitive to those frequencies.
- the apparatus for changing the particle size distribution may be a cyclone.
- the control arrangement may be automated.
- Figure 1 shows a schematic diagram of a control arrangement according to the invention having a feedback control loop
- Graph 5 shows a graph of the power law coefficient ⁇ in the final recovery zone as shown in graph 4 as a comparison of values obtained from carrying out multivariable polynomial regression of equation 4a and fitting of equation 4a, plotted against solids density;
- Graph 6 shows a graph of the power law coefficient ⁇ in the final recovery zone as shown in graph 4 and 5 as a comparison of values obtained from carrying out multivariable polynomial regression of equation 4a and fitting of equation 4a, plotted against tons per hour (tph) of ore feed;
- Graph 7 shows a graph of the power law coefficient ⁇ in the final recovery zone as shown in graph 4, 5, and 6 as a comparison of values obtained from carrying out multivariable polynomial regression of equation 4a and fitting of equation 4a, plotted against spiral lengths of 5 and 7 turns;
- Graph 10 shows a graph of experimental results showing the influence of variation in flow rate on distance from spiral centre column to silica/ilmenite interface
- Graph 11 shows a graph showing a comparison of results predicted by the mathematical model against experimental results showing the influence of spiral profile on the distance from spiral centre column to silica/ilmenite interface
- the mathematical model incorporates a plurality of slurry stream parameters, each of which have an effect on the efficiency of the separation process
- the absolute values of each of these parameters must either be measured in order to solve the mathematical model, and to calculate how the efficiency of the separation process may be optimized by varying any of the other parameters that are adjustable.
- relative values for the parameters may be measured (i.e. the difference in these parameters) in order to enable relative control of the adjustment means by the control system. Any combination of these parameters can then subsequently be adjusted by the adjustment means 120 in order to optimize the efficiency of the separation process.
- the measuring means 50 will be in the form of electronic transducers that detect the values for slurry parameters in either the feed, concentrate tailings or separator slurry streams, and send electronic signals M1 and M2 (as shown in Figures 1 to 4) to the calculation means 70, in the form of a control system 130.
- the control system 130 will include an electronic processor (not shown) and memory storage facility like a hard disc or the like (not shown). The calculation of how the efficiency of the separation process may be optimized will then be performed using the mathematical model stored in the control system 130.
- the control system 130 then sends control signals to the adjustment means 120, which then adjust parameters X1 and X2 (as shown in Figure 1).
- the number of measured signals IVI will correspond to the number of parameters in the mathematical model where absolute measurements are being measured by the measuring means. However, where relative measurements are being measured by the measuring means, only any changes in parameters need be measured. The number of adjusted parameters X need not correspond to the number of measured parameters.
- the adjustment of the slurry parameters will depend on the practical constraints of which parameters are open to adjustment, and the selection of which parameters are adjusted, and the proportions in which they are adjusted, will depend on a wide variety of factors, such as the difficulties, cost and available control (i.e. the amplification) of adjusting certain slurry parameters. The control of these adjustment factors may be programmed into the control system.
- the control system 130 will send control signals to the adjustment means 120.
- the adjustment means can be a wide variety of apparatus, which can change any one of the slurry stream parameters and/or any combination of them.
- the adjustment means 120 may adjust a slurry parameter in a predetermined fashion depending on the relative difference in the measured parameter.
- the measuring means 50 can measure slurry stream parameters from either the feed slurry stream 110, the slurry stream as it passes through the spiral separators 60 or either of the tailings slurry stream 80 or the concentrate slurry stream 90.
- the optical characteristics of the slurry stream as it operationally separates in the spiral separators 60 can be measured. Specifically, the location of a visible concentrate, tailings or middlings bands may be detected optically. It is envisaged that these bands may further be detected by means of other frequencies besides optical light, such as infrared, microwave or x-ray frequencies.
- the adjustment means 120 can comprise any one of the apparatus selected from the group consisting of
- the fluid addition means can comprise apparatus for the addition of fluid to the system, the fluid being any one of the group consisting of dilution water, slurry and any combination thereof.
- control arrangement 200 will be automated, and that it will operate by means of either a feedback loop (as shown in Figure 1) or a feed forward loop (not shown).
- control system 130 uses a mathematical model of the general form:
- Rvf is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function ⁇ is a function of a plurality of slurry stream parameters. It should be noted that the control system may use a mathematical model of any other general form.
- ⁇ /(Ps, I 8 , ⁇ s , Xf, pv, pt, m s Q s ⁇ ) (4b)
- the mathematical model used in the electronic control system 130 is completed by fitting coefficient a, as described in equation 1 in the prior art (in the initial recovery zone), and mathematical smoothing of the discontinuity between the initial recover zone and final recovery zone in a similar fashion to described by Holland-Batt (1990).
- a research project was initiated at the University of Pretoria, South Africa, whereby an optical transducer (not shown) was used which provides a light intensity signal (as shown in figure 3) that correlates with the color of the mineral in the separated slurry streams in the spiral separator.
- the optical transducer will provide the feedback required to automatically adjust the control system's output.
- Test work was performed using an artificial ore consisting of ilmenite and silica mixed in different ratios.
- the ilmenite and silica samples were obtained from Richards Bay in Kwazulu Natal on the South African east coast.
- the ilmenite and silica were combined in ratios that were close to the known average Total Heavy Mineral (THM) feed grade from Hillendale Mine.
- TBM Total Heavy Mineral
- Graph 1 1 shows a comparison of results predicted by the mathematical model against experimental results showing the influence of spiral profile on the distance from spiral center column to silica/ilmenite interface.
- measuring means 50 may be used, which may provide many different control system inputs, such as run of mine feed grade data, which would allow the use of a feedforward control loops, as well as other inputs which would allow feedback conrol loops.
- slurry stream parameters may be measured from the slurry stream in the separator, from the feed slurry stream, from the concentrate slurry stream or from the tailings slurry stream, where applicable.
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- Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
Abstract
The invention provides a control arrangement for conrolling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, comprising measuring means for measuring a plurality of slurry stream parameters; calculation means for calculating how at least one feed slurry stream parameter may be adjusted so as to optimize the efficiency of the separation process; and adjustment means for adjusting at least one feed slurry stream parameter in response to the result of the calculation from the calculation means.
Description
SPIRAL SEPARATOR AND CONTROL SYSTEM
Technical field
This invention relates to a spiral separator, a control system and a method therefor.
Introduction and background to the invention
Generally, a spiral separator comprises a helical or spiral trough mounted about an upright column, alternately within a frame structure. During operation of a spiral separator of this kind, slurry, containing mineral particles to be separated (or concentrated) is fed to the top of the helical trough. As the slurry descends in the trough under gravity, the mineral bearing particles in the slurry migrate radially outwardly under centrifugal forces according to size or specific gravity. Smaller or less dense particles move under the action of centrifugal forces in a radially outward direction while denser particles migrate radially inward towards the central column.
The term "beneficiation" for purposes of this specification shall be interpreted as to include separation and concentration.
In a large beneficiating plant, banks of spiral separators may be operating simultaneously, so that a small change in efficiency across the banks may result in large deviations in production of concentrated minerals. While the feed systems that provide inflow to a plant are designed for optimum efficiency of the spiral separator banks for generally expected operational conditions and variations, in practice the conditions and variables fluctuate over time due to changing mineralogical, feed and operational conditions and variables in the process.
Attempts have been made in the past to design systems and devices that allow for control of the spiral separators to account for these changing conditions. An example of such a device is a spiral having an adjustable splitter, which may be adjusted according to varying operating conditions. A
disadvantage of these systems is that they are impractical, due to the large number of spiral separators that need to be adjusted, as well as the dynamic nature of the process and the need for constant adjustment. Large mineral processing plants can have thousands of spiral separators. The adjustment of splitters is time consuming, and if neglected, causes either losses or product quality problems.
Attempts have also been made to control the banks of spiral separators as a whole by designing systems which allow sections of the bank of spirals to be switched off or excluded from the beneficiation process, particularly when the plant is operating below design capacity, effectively increasing the flow rate through the spiral separators which are still operating.
It is known that spirals are sensitive to feed rate fluctuations. If feed rates drop, then feed slurry streams are diverted from a proportion of the spirals, thereby increasing the volume flow rate through the remaining spirals and avoiding the effects which would occur otherwise.
Yet other prior art systems are disclosed in US Patent No's. US 3,235,080 and US 3,235,079. US 3,235,080 discloses a control system for a bank of spirals which measures the pulp density of the upstream slurry flow being pumped, as well as the slurry feed pump speed (as an indication of volume flow rate). These measurements are then multiplied, in order to indicate the mass flow rate to the spirals. Further a belt scale is used to measure the mass flow rate of the dewatered concentrate after separation.
The spiral feed pump speed is then used, together with a pump box and level sensor, to control the solids to water ratio (i.e. the density) of the feed slurry. Further, measurements from the slurry density meter, the slurry pump speed and the belt scale are sent to a proportional relay which controls the number of spirals that are engaged in the separation process, and the amount of wash water mixed with the slurry.
The slurry density is controlled to a constant density, and the control of the wash water together with the inclusion or exclusion of the spirals are mechanisms used to control the flow rate and density of the flow down the spirals to a predetermined value. In this system, a slurry parameter is either measured or calculated, and then that parameter is controlled by various mechanisms in order to maintain it at a constant level, or within a set design range.
US 3,235,079 discloses a method and apparatus for controlling spiral separators wherein the pulp density of the feed flow to a bank of spirals is measured by a pulp density meter, and, depending on the measurement from the pulp density meter, a splitter is positioned automatically to split the downstream concentrate stream to divert part of it back to the feed flow, thereby changing the density of the feed flow.
This system measures the slurry density of the feed stream and controls the same parameter to a constant value or within a predetermined range.
These methods all recognise the detrimental effect of feed parameter fluctuations. To counter the fluctuations, methods are proposed to correct these variables back to their design value for the separation system. While these systems correct fluctuations in feed parameters and try to control them to within a design range, they do not recognise the relationship between the variables and do not control the actual efficiency of the separation as a design parameter.
The systems mentioned above all attempt to maintain one or more parameters at constant design levels, in the hope that the operation of the system at these levels will be operating at an optimum efficiency. However, the feed slurry conditions and parameters may fluctuate to such an extent that the original design assumptions may be incorrect, and control of such a measured parameter at predetermined levels may not necessarily result in optimum efficiency of the separation process.
A further disadvantage of these prior art systems is that they frequently involve the recirculation of slurry that has already been through the system, in order to increase the chances of collecting those minerals that were not collected during the first separation process. Such recirculation reduces the throughput of the separation process.
It is known that the shape of a release curve in a mineral recovery process can be approximated by a number of mathematical models, including a simple power law function such as the mathematical model proposed in 1990 by Holland-Batt [Holland Batt, AB. (1990): Interpretation of spiral and sluice tests, Trans. Instn. Min. Metall (sect C: Mineral Process Extr. Metall), 99]. In this publication, the authors reported that the shape of release curves in spiral applications could be described by a combination of a linear function in an initial recovery zone, and a power-law function in a final recovery zone.
The proposed recovery function was formulated as
RvJ= aRM (1 )
where
RVι i is the recovery of valuable mineral in the initial recovery zone
RM is the mass recovery; and a is a coefficient
For the initial recovery zone, where, under ideal conditions, the slope of the recovery function is equal to the maximum possible upgrade ratio
α = ■ (2)
X i
where
a is a coefficient;
C/ is the initial concentrate grade; and
Xf is the feed grade.
The recovery of valuable mineral in the final recovery zone was expressed as a power-law function of the form
where
RVf is the recovery of valuable mineral in the final recovery zone; RM is the mass recovery; c and b are coefficients; and (F-F0) is a change in feed rate.
The discontinuity between the initial and final recovery zones can be smoothed with a suitable function.
It is further known that the shape of the release curve is affected by a range design and operating variables, which include spiral trough geometry, represented by profile shape, spiral length and pitch, feed grade, feed mineral density, volumetric and mass flow, as well as a range of other variables which are relevant but often not readily accessible in metallurgical testwork such as slurry viscosity, particle size distribution, particle shape, or mineral liberation. Those variables have to have an effect on the coefficient b in equation (3).
For the purposes of this specification, the term "slurry stream parameter" shall be defined to mean any of the parameters selected from the group of:
> the percentage solids in the slurry stream, > the feed grade of the slurry stream,
> volumetric flow rate of the slurry stream,
> optical characteristics of the slurry stream,
> separator trough profile characteristics,
> spiral length, spiral trough angle,
> spiral trough pitch,
> valuable mineral density,
> gangue density, > mass flow rate,
> slurry flow rate,
> slurry viscosity,
> particle size distribution,
> slurry particle shape, > mineral liberation; and
> any combination of the above.
Object of the Invention
It is accordingly an objective of this invention to provide a spiral separator and control system arrangement that at least partially alleviates the abovementioned disadvantages and/or offers an alternative to the prior art.
Disclosure of the Invention
According to a first aspect of the invention, there is provided a control arrangement for controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, comprising
> measuring means for measuring a plurality of slurry stream parameters;
> calculation means for calculating how at least one feed slurry stream parameter may be adjusted so as to optimize the efficiency of the separation process; and
> adjustment means for adjusting at least one feed slurry stream parameter in response to the result of the calculation from the calculation means.
The calculation means may utilise a mathematical model for calculating how the at least one slurry parameter may be adjusted.
The calculation means may calculate how a plurality of slurry parameters may be adjusted so as to increase the efficiency of the separation process.
The adjustment means may adjust a plurality of feed slurry stream parameters in response to the measurement of the measured slurry stream parameter.
The control arrangement may include a control system for controlling the adjustment of the feed slurry stream parameter.
The control arrangement may be electronic.
The mathematical model may incorporate a plurality of slurry stream parameters.
The mathematical model may include a function of the form:
Rv.f = RM where
Rvf is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function α is a function of a plurality of slurry stream parameters.
The function for α may be predetermined.
The function for α may have been predetermined by means of polynomial regression by means of experimental analysis.
The measuring means may measure a slurry stream parameter of the feed slurry stream.
The measuring means may measure a slurry stream parameter of the concentrate slurry stream.
The measuring means may measure a slurry stream parameter of the tailings slurry stream.
The parameter of optical characteristics of the slurry stream may be the optical characteristics of the slurry stream as it is being operationally separated by the spiral separator into concentrate bands and/or tailings bands and/or middlings bands.
The adjustment means may comprise any one of the apparatus selected from the group consisting of > apparatus for recycling a product stream into a feed stream,
> fluid addition means,
> dewatering apparatus,
> apparatus for changing the number of spirals,
> apparatus for splitting the feed to the spiral separator, > any apparatus suitable for achieving a variation in a slurry stream parameter;
> apparatus for changing particle size distribution of the slurry stream; and/or
> any combination of the above.
The apparatus for changing the particle size distribution may be a cyclone.
The fluid addition means may comprise apparatus for the addition of fluid to the system, the fluid being any one of the group consisting of dilution water, slurry and any combination thereof.
The control arrangement may be automated.
The control arrangement may operate by means of a feedback loop.
Thw control arrangemnet ay utilise a predictive model in a feedforward loop.
The control arrangement may operate by means of a feedforward loop.
According to a second aspect of the invention, there is provided a method of controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, the method including the steps of > measuring a plurality of slurry stream parameters;
> calculating how at least one adjustable feed slurry stream parameter may be adjusted so as to increase the efficiency of the separation process; and
> adjusting a feed slurry stream parameter in response to the result of the calculation.
The calculation may be in accordance with a mathematical model.
A plurality of feed stream parameters may be adjusted in response to the measurement of the measured slurry stream parameter.
The calculation may be carried out by electronic means.
The feed slurry characteristic may be altered by the addition of fluid.
The fluid added to the feed slurry stream may be dilution water.
The feed slurry characteristic may be adjusted by the addition of fluid, dewatering the slurry stream, passing the slurry stream through a cyclone, changing the number of spirals, splitting the feed slurry stream to the spiral separator, changing the particle size distribution, and/or any combination thereof.
The adjustment of the feed slurry characteristic may be accomplished automatically by means of a looped feedback control system.
The adjustment of the feed slurry characteristic may be accomplished automatically by means of a looped feedforward control system.
The adjustment of the feed slurry stream may be accomplished by carrying out an action selected from the group of
> recycling either of the concentrate stream or tailing stream into the feed stream,
> adding fluid
> dewatering the feed slurry stream,
> passing the slurry through a cyclone,
> increasing or decreasing the number of spirals, > splitting the feed slurry stream to the spiral separator,
> adjusting the particle size within the feed slurry stream; and/or
> any combination of the above methods.
According to a third aspect of the invention, there is provided a control arrangement for controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, comprising
> measuring means for measuring a plurality of slurry stream parameters;
> adjustment means for adjusting at least one feed slurry stream parameter in accordance with a predetermined mathematical model of the separation process in order to optimize the efficiency of the separation process.
The measuring means may measure a slurry parameter or a change in a slurry parameter.
At least one of the measured slurry parameters may be the slurry feed grade.
At least one of the measured slurry parameters may be a parameter directly related to the efficiency of the separation process.
The adjusted slurry stream parameter may not be the same slurry parameter that was measured.
A slurry parameter directly related to the efficiency of the separation process may be the optical characteristics of the separated slurry bands.
The calculation means may calculate how a plurality of slurry parameters may be adjusted so as to increase the efficiency of the separation process.
The adjustment means may adjust a plurality of feed slurry stream parameters in response to the measurement of the measured slurry stream parameter.
The control arrangement may include a control system for controlling the adjustment of the feed slurry stream parameter.
The control arrangement may be electronic.
The mathematical model may incorporate a plurality of slurry stream parameters.
The mathematical model may incorporate the measured slurry stream parameters.
The mathematical model may include a variable for the feed grade of the feed slurry stream.
The adjustment means may adjust a parameter in response to a change in feed grade of the feed slurry stream.
The adjustment means may adjust a plurality of parameter in response to a change in feed grade of the feed slurry stream.
The mathematical model may include a variable for the efficiency of the separation process.
The mathematical model may include a variable for a slurry stream parameter that is directly related to the efficiency of the separation process.
The mathematical model may include a function of the form:
R = R" where RVf is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function α is a function of a plurality of slurry stream parameters.
The function for α may be predetermined.
The function for α may have been predetermined by means of polynomial regression by means of experimental analysis.
The measuring means may measure a slurry stream parameter in the feed slurry stream.
The measuring means may measure a slurry stream parameter in the concentrate slurry stream.
The measuring means may measure a slurry stream parameter in the tailings slurry stream.
The parameter of optical characteristics of the slurry stream may be the optical characteristics of the slurry stream as it is being operationally separated by the spiral separator into concentrate bands and/or tailings bands and/or middlings bands.
The optical characteristic parameter may be the optical characteristics of the slurry stream after being radiated by various frequencies of radiation, and when monitored through devices sensitive to those frequencies.
The radiation may be x-ray, ultraviolet, infra-red, microwave, and the like.
The adjustment means may comprise any one of the apparatus selected from the group consisting of
> apparatus for recycling a product stream into a feed stream, > fluid addition means,
> dewatering apparatus,
> apparatus for changing the number of spirals,
> apparatus for splitting the feed to the spiral separator,
> any apparatus suitable for achieving a variation in a slurry stream parameter;
> apparatus for changing particle size distribution of the slurry stream; and/or
> any combination of the above.
The apparatus for changing the particle size distribution may be a cyclone.
The fluid addition means may comprise apparatus for the addition of fluid to the system, the fluid being any one of the group consisting of dilution water, slurry and any combination thereof.
The control arrangement may be automated.
The control arrangement may operate by means of a feedback loop.
The control arrangement may operate by means of a feedforward loop.
These and other features of the invention are described in more detail below.
Specific Embodiment of the Invention
A preferred embodiment of the invention will now be described by way of a non-limiting example only, with reference to the accompanying drawings in which:
Figure 1 shows a schematic diagram of a control arrangement according to the invention having a feedback control loop;
Figure 2 shows a schematic diagram of a control arrangement according to the invention as it may be incorporated into a flow sheet solver with two internal recycles balancing a three-stage spiral circuit;
Figure 3 is a plot showing light intensity signal from an optical transducer drawn across a flow profile in a spiral separator, in which the interface is clearly visible;
Graph 1 shows a graph of Valuable Mineral Recovery versus Total Recovery for Chromite type RSA-UG2, feed grade 42.49% Cr2O3, spiral type: SC21 , 5-turn;
Graph 2 shows a graph of Valuable Mineral Recovery versus Total Recovery for Beach Sands (USA), feed grade 1.96% VHM, spiral type: SC20LG, 7-turn,1.42 tph;
Graph 3 shows a graph of Valuable Mineral Recovery versus Total Recovery for Beach Sands (USA), feed grade 2.26% VHM, spiral type: SC20LG, 7-turn,1.03 tph;
Graph 4 shows a graph of the power law coefficient α in the final recovery zone as a comparison of values obtained from carrying out multivariable polynomial regression of equation 4a and fitting of equation 4a, plotted against feed grade;
Graph 5 shows a graph of the power law coefficient α in the final recovery zone as shown in graph 4 as a comparison of values obtained from carrying out multivariable polynomial regression of equation 4a and fitting of equation 4a, plotted against solids density;
Graph 6 shows a graph of the power law coefficient α in the final recovery zone as shown in graph 4 and 5 as a comparison of values obtained from carrying out multivariable polynomial regression of equation 4a and fitting of equation 4a, plotted against tons per hour (tph) of ore feed;
Graph 7 shows a graph of the power law coefficient α in the final recovery zone as shown in graph 4, 5, and 6 as a comparison of values obtained from carrying out multivariable polynomial regression of equation 4a and fitting of equation 4a, plotted against spiral lengths of 5 and 7 turns;
Graph 8 shows a graph of experimental results showing the influence of variation in grade on the distance from spiral centre column to silica/ilmenite interface;
Graph 9 shows a graph of experimental results showing the influence of variation in pulp density on distance from spiral centre column to silica/ilmenite interface;
Graph 10 shows a graph of experimental results showing the influence of variation in flow rate on distance from spiral centre column to silica/ilmenite interface;
Graph 11 shows a graph showing a comparison of results predicted by the mathematical model against experimental results showing the influence of spiral profile on the distance from spiral centre column to silica/ilmenite interface;
The same reference numerals are used to denote corresponding parts in the accompanying drawings.
According to the invention, there is provided a control arrangement 200 for controlling the separation of a feed slurry stream 110 flowing to a bank of spiral separators 60 into at least a concentrate slurry stream 90 and a tailings slurry stream 80 (as shown in Figure 1) in a separation process, comprising measuring means 50 for measuring a plurality of slurry stream parameters; calculation means 70, in the form of an electronic control system 130, for calculating how at least one feed slurry stream parameter may be adjusted so as to optimize the efficiency of the separation process; and adjustment means 120 for adjusting at least one feed slurry stream parameter in response to the result of the calculation by the calculation means 70.
The electronic control system 130 utilises a mathematical model (not shown) for calculating how the at least one slurry parameter may be adjusted. The mathematical model models the efficiency of the separation process based on a number of variables, including feed grade. The mathematical model relates the slurry parameters to either the efficiency of the separation process, or to another parameter which is directly related to or indicative of
the efficiency of the separation process. The mathematical model takes into account at least two slurry stream parameters and their effect on the efficiency of the separation process.
As the mathematical model incorporates a plurality of slurry stream parameters, each of which have an effect on the efficiency of the separation process, the absolute values of each of these parameters must either be measured in order to solve the mathematical model, and to calculate how the efficiency of the separation process may be optimized by varying any of the other parameters that are adjustable. Alternately, relative values for the parameters may be measured (i.e. the difference in these parameters) in order to enable relative control of the adjustment means by the control system. Any combination of these parameters can then subsequently be adjusted by the adjustment means 120 in order to optimize the efficiency of the separation process.
It is envisaged that, using this control arrangement, fluctuations in parameters that are not adjustable by the adjustment means may be accounted for by adjustments of other adjustable parameters in order to optimize efficiency of the separation process.
It is envisaged that the measuring means 50 will be in the form of electronic transducers that detect the values for slurry parameters in either the feed, concentrate tailings or separator slurry streams, and send electronic signals M1 and M2 (as shown in Figures 1 to 4) to the calculation means 70, in the form of a control system 130. It is envisaged that the control system 130 will include an electronic processor (not shown) and memory storage facility like a hard disc or the like (not shown). The calculation of how the efficiency of the separation process may be optimized will then be performed using the mathematical model stored in the control system 130. The control system 130 then sends control signals to the adjustment means 120, which then adjust parameters X1 and X2 (as shown in Figure 1).
Generally the number of measured signals IVI will correspond to the number of parameters in the mathematical model where absolute measurements are being measured by the measuring means. However, where relative measurements are being measured by the measuring means, only any changes in parameters need be measured. The number of adjusted parameters X need not correspond to the number of measured parameters. Once measurements have been measured by the measuring means, the adjustment of the slurry parameters will depend on the practical constraints of which parameters are open to adjustment, and the selection of which parameters are adjusted, and the proportions in which they are adjusted, will depend on a wide variety of factors, such as the difficulties, cost and available control (i.e. the amplification) of adjusting certain slurry parameters. The control of these adjustment factors may be programmed into the control system.
Once the calculation of how the separation process is to be optimized has been carried out, the control system 130 will send control signals to the adjustment means 120. It is envisaged that the adjustment means can be a wide variety of apparatus, which can change any one of the slurry stream parameters and/or any combination of them. Alternatively, where relative measurements are being made by the measuring means 50, the adjustment means 120 may adjust a slurry parameter in a predetermined fashion depending on the relative difference in the measured parameter.
It is envisaged that the measuring means 50 can measure slurry stream parameters from either the feed slurry stream 110, the slurry stream as it passes through the spiral separators 60 or either of the tailings slurry stream 80 or the concentrate slurry stream 90.
In one example, the optical characteristics of the slurry stream as it operationally separates in the spiral separators 60 can be measured. Specifically, the location of a visible concentrate, tailings or middlings bands may be detected optically. It is envisaged that these bands may further be
detected by means of other frequencies besides optical light, such as infrared, microwave or x-ray frequencies.
It is envisaged that the adjustment means 120 can comprise any one of the apparatus selected from the group consisting of
> apparatus for recycling a product stream into a feed stream,
> fluid addition means,
> dewatering apparatus,
> apparatus for passing the slurry through a cyclone, > apparatus for changing the number of spirals,
> apparatus for splitting the feed to the spiral separator,
> apparatus for changing particle size distribution of the slurry stream and/or any combination thereof.
These apparatus for adjusting slurry parameters are not shown in the figures.
In one embodiment, the fluid addition means can comprise apparatus for the addition of fluid to the system, the fluid being any one of the group consisting of dilution water, slurry and any combination thereof.
It is further envisaged that the control arrangement 200 will be automated, and that it will operate by means of either a feedback loop (as shown in Figure 1) or a feed forward loop (not shown).
In a typical embodiment, the control system 130 uses a mathematical model of the general form:
Rvf = Rm α (4a) where
Rvf is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function α is a function of a plurality of slurry stream parameters.
It should be noted that the control system may use a mathematical model of any other general form.
Specifically, the function for α is represented by α = /(Ps, I8, Θs, Xf, pv, pt, ms Qsι) (4b) where
Θs spiral trough angle/pitch pt gangue density Pv valuable mineral density iris mass flow solids
Ps profile coefficent spiral trough Qsi slurry flowrate Xf feed grade
In a preferred embodiment, the mathematical model will include the slurry feed grade as a parameter, together with other adjustable parameters. When the slurry feed grade fluctuates, the measuring means 50 will measure the change, and the adjustment means 120 will be able to adjust other adjustable slurry parameters to allow for the fluctuations in slurry feed grade.
In another preferred embodiment, the mathematical model includes a parameter which is directly related to or indicative of the efficiency of the separation process. Such a parameter would typically be the distance of the interface 300 between separated bands in the separators from the splitter device (not shown) on the separators 60. The further the interface 300 is from the splitter, the less efficient the separation process will be. When the measuring means measures a change in distance of the interface 300 from the splitter, the adjustment means 120 can adjust any number of other slurry parameters so that the distance between the interface 300 and the splitter is minimized.
A sufficiently large database of metallurgical testwork data was available to the applicant to evaluate the described model, from which 217 data sets were
chosen for fitting of model parameters. Each data set consisted of usually 8 measured data points along the release curve, against which the exponential coefficient function α was evaluated through least squares fit according to equation 4a, (as illustrated in graphs 1 to 3). The values obtained for α, after evaluation of a range of possible functional relationships, were then fitted by multivariable polynomial regression against the design and operating variables listed above, which yielded a relationship for equation 4b.
The evaluation of this relationship against some of the selected variables is illustrated in graphs 4 to 7. It may be seen that the power law coefficient is reasonably well described within the range of variables chosen.
The mathematical model used in the electronic control system 130 is completed by fitting coefficient a, as described in equation 1 in the prior art (in the initial recovery zone), and mathematical smoothing of the discontinuity between the initial recover zone and final recovery zone in a similar fashion to described by Holland-Batt (1990).
In this manner, equations 1 , 4a and 4b can easily be integrated into a spreadsheet or other convenient means. An example is illustrated in figure 2.
This allows the evaluation of various modifications to a given gravity separation circuit, such as the variation of feed properties, change in recycle streams, or the selection of different spiral geometries, and the evaluation of the response of the selected spiral concentrator to the change in operating variables.
It is envisaged that this mathematical model can be used in the development of flowsheets for a certain suite of minerals, and this can be utilized to reduce the number of tests required to arrive at an optimum circuit, because in combination with the existing database of the regression parameters of equation 4b, the response function for the particular mineral can be established with only a small number of additional experiments.
Other effects can easily be accounted for, such as the depression of the release curve as a consequence of the presence of high slimes content, which can be represented by increasing the coefficient α by a constant value c/to form the equation
Rv, = aRm {a+d) (4c)
The mathematical model set out above has practical applications in the control arrangement 200. As an example, as mentioned before, one of the difficulties in operating spiral plants (not shown) is the required adjustment of splitters (not shown) disposed in the slurry streams on each spiral separator 60 to accommodate the fluctuations of feed slurry stream 110 properties that may occur during mining operations.
It is envisaged that the control arrangement 200 will allow manipulation of the radial position of the interface 300 (shown in figure 3) between the separated slurry streams in the spiral separator, so that the splitter position may be left unchanged. The radial position of the interface 300 is a function of the operating variables, and the results reported above confirm that the operating variables are correlated in various ways. For example, graphs 4 and 6 show that feed grade and feed rate are both positively correlated with the coefficient α, which describes the mineral recovery.
To further illustrate a preferred embodiment, a research project was initiated at the University of Pretoria, South Africa, whereby an optical transducer (not shown) was used which provides a light intensity signal (as shown in figure 3) that correlates with the color of the mineral in the separated slurry streams in the spiral separator. In a process control application, the optical transducer will provide the feedback required to automatically adjust the control system's output.
While visible light was used in this embodiment, it is envisaged that a wide variety of radiation types may be used, including x-ray, infra-red, microwave,
ultraviolet light, and the like, together with monitoring apparatus which is is sensitive to these types of radiation.
Test work was performed using an artificial ore consisting of ilmenite and silica mixed in different ratios. The ilmenite and silica samples were obtained from Richards Bay in Kwazulu Natal on the South African east coast. The ilmenite and silica were combined in ratios that were close to the known average Total Heavy Mineral (THM) feed grade from Hillendale Mine.
The feed parameters that were adjusted in order to quantify the effect on the separation efficiency were percentage solids, feed grade and volumetric flow rate. Changes in these parameters were related to the radial position of the interface 300 on the spiral separator 60. An empirical model was then developed using factorial design to relate the three different feed variables to the interface 300 distance from the centre column.
A three-factor experimental plan was designed around the standard operating conditions of the SC22 mineral spiral, and the three variables: feed grade, volumetric flow rate and feed density were normalised in accordance with standard statistical procedure according to equation 5.
χ = (Grade) -15
10 (5)
(%Solids) -30
X, -
20
(Flowrate)-3.6
X3 =
The effects of the three variables are illustrated in graphs 8 to 10. As expected, all three variables are positively correlated with the radial position of the interface 300.
For control purposes, a linear model was regarded as sufficient as the control system 130 requires information on the direction of the output action (increase or reduction) and the magnitude (amplification) only. The obtained model was then refined as
where r= radial distance of of the gangue /concentrate interface from the centre column
For a given fixed splitter position, the position of the concentrate/gangue interface will be directly related to the separation efficiency.
Graph 1 1 shows a comparison of results predicted by the mathematical model against experimental results showing the influence of spiral profile on the distance from spiral center column to silica/ilmenite interface.
In this manner, a signal from a measuring means 50 in the form of optical transducer may be used in combination with a mathematical model of the separation process, incorporating a number of slurry stream parameters, in a control system to control the separation process.
It is envisaged that many different measuring means 50 may be used, which may provide many different control system inputs, such as run of mine feed grade data, which would allow the use of a feedforward control loops, as well as other inputs which would allow feedback conrol loops. Further, slurry stream parameters may be measured from the slurry stream in the separator, from the feed slurry stream, from the concentrate slurry stream or from the tailings slurry stream, where applicable.
In the manner described above, it is possible to offset the effect of changing or inconsistent variabies in the mathematical model (such as feed grade) by
adjustment of other variables in the model (such as volumetric flow, feed density, or others), thereby maximising the efficiency of the separation process.
It is envisaged that in plant practice some caveats would exist, such as the presence of slimes preventing the visual detection of the interface, or the effects of the control arrangement on the plant mass balance. In such instances, alternative slurry stream parameters may be measured, such as slurry density.
Further, the adjustment means 120 may be one of many alternative aparatuses, including apparatus for recycling a product stream into a feed stream, fluid addition means for adding fluid such as dilution water, slurry or any combination of these to the feed slurry stream, dewatering apparatus, apparatus for passing the slurry through a cyclone, apparatus for changing the number of spirals, apparatus for splitting the feed to the spiral separator, apparatus for changing particle size distribution of the slurry stream and/or any combination thereof.
It will be appreciated that numerous embodiments of the invention are possible without with out departing from the scope of the invention.
Claims
1. A control arrangement for controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, including: measuring means for measuring a plurality of slurry stream parameters; calculation means for calculating how at least one feed slurry stream parameter is to be adjusted so as to optimize the efficiency of the separation process; and adjustment means for adjusting at least one feed slurry stream parameter in response to the result of the calculation from the calculation means.
2. The control arrangement of claim 1 wherein the calculation means utilizes a mathematical model for calculating how the at least one slurry parameter is to be adjusted.
3. The control arrangement of claim 1 or claim 2 wherein the calculation means calculates how a plurality of slurry parameters are to be adjusted so as to increase the efficiency of the separation process.
4. The control arrangement of any one of the preceding claims wherein the adjustment means adjusts a plurality of feed slurry stream parameters in response to the measurement of the measured slurry stream parameter.
5. The control arrangement of any one of the preceding claims including a control system for controlling the adjustment of the feed slurry stream parameter.
6. The control arrangement of claim 5 wherein the control system is electronic.
7. The control arrangement of any one of claims 2 to 6 wherein the mathematical model incorporates a plurality of slurry stream parameters.
8, The control arrangement of any one of claims 2 to 7 wherein the mathematical model includes a function of the form
R = Ra where
RVf is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function α is a function of a plurality of slurry stream parameters.
9. The control arrangement of claim 8 wherein the function for α is predetermined.
10. The control arrangement of claim 9 wherein the function for α has been predetermined by means of polynomial regression by means of experimental analysis.
11. The control arrangement of any one of the preceding claims wherein the measuring means measures a slurry stream parameter of the feed slurry stream.
12. The control arrangement of any one of the preceding claims wherein the measuring means measures a slurry stream parameter of the concentrate slurry stream.
13. The control arrangement of any one of the preceding claims wherein the measuring means measures a slurry stream parameter of the tailings slurry stream.
14. The control arrangement of any one of the preceding claims wherein the measuring means measures a parameter of optical characteristics of the slurry stream.
15. The control arrangement of claim 14 wherein the parameter of optical characteristics of the slurry stream is the optical characteristics of the slurry stream as it is being operationally separated by the spiral separator into concentrate bands and/or tailings bands and/or middlings bands.
16. The control arrangement of claim 14 or claim 15 wherein the parameter of optical characteristics is the optical characteristics of the slurry stream after being radiated by various frequencies of radiation, and when monitored through devices sensitive to those frequencies.
17. The control arrangement of claim 16 wherein the radiation is selected from the group consisting of x-ray, ultraviolet, infrared and microwave.
18. The control arrangement of any one of the preceding claims wherein the adjustment means comprises any one or a combination of the apparatus selected from the group consisting of apparatus for recycling a product stream into a feed stream, fluid addition means, dewatering apparatus, apparatus for changing the number of spirals, apparatus for splitting the feed to the spiral separator, any apparatus suitable for achieving a variation in a slurry stream parameter and apparatus for changing particle size distribution of the slurry stream.
19. The control arrangement of claim 18 wherein the apparatus for changing the particle size distribution is a cyclone.
20. The control arrangement of claim 18 wherein the fluid addition means comprises apparatus for the addition of fluid to the system, the fluid being any one of the group consisting of dilution water, slurry and any combination thereof.
21. The control arrangement of any one of the preceding claims wherein the control arranngement is automated.
22. The control arrangement of any one of the preceding claims wherein the control arrangement is operated by means of a feedback loop.
23. The control arrangement of any one of claims 1 to 21 wherein the control arrangement is operated by means of a feed forward loop
24. The control arrangement of claim 22 or 23 wherein the control arrangement utilizes a predictive model in the control system..
25. A control arrangement for controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, comprising measuring means for measuring a plurality of slurry stream parameters; and adjustment means for adjusting at least one feed slurry stream parameter in accordance with a predetermined mathematical model of the separation process in order to optimize the efficiency of the separation process.
26. The control arrangement of claim 25 wherein the measuring means measures a slurry parameter or a change in a slurry parameter.
27. The control arrangement of any one of claims 25 to 26 wherein at least one of the measured slurry parameters is the slurry feed grade.
28. The control arrangement of any one of claims 25 to 27 wherein at least one of the measured slurry parameters is a parameter directly related to the efficiency of the separation process.
29. The control arrangement of any one of claims 25 to 28 wherein the adjusted slurry stream parameter is not the same slurry parameter as the measured parameter.
30. The control arrangement of any one of claims 25 to 29 wherein a measured parameter directly related to the efficiency of the separation process is the optical characteristics of the separated slurry bands.
31. The control arrangement of claim 30 wherein the parameter of optical characteristics of the slurry stream is the optical characteristics of the slurry stream as it is being operationally separated by the spiral separator into concentrate bands and/or tailings bands and/or middlings bands.
32. The control arrangement of claim 31 wherein the parameter of optical characteristics is the optical characteristics of the slurry stream after being radiated by various frequencies of radiation, and when monitored through devices sensitive to those frequencies.
33. The control arrangement of any one of claims 25 to 32 wherein the adjustment means adjusts a plurality of feed slurry stream parameters in response to the measurement of the measured slurry stream parameter.
34. The control arrangement of any one of claims 25 to 33 wherein the control arrangement includes a control system for controlling the adjustment of the feed slurry stream parameter.
35. The control arrangement of claim 34 wherein the control arrangement is electronic.
36. The control arrangement of any one of claims 25 to 35 wherein the mathematical model incorporates a plurality of slurry stream parameters.
37. The control arrangement of any one of claims 25 to 36 wherein the mathematical model incorporates the measured slurry stream parameters.
38. The control arrangement of any one of claims 25 to 37 wherein the mathematical model includes a variable for the feed grade of the feed slurry stream.
39. The control arrangement of claim 38 wherein the adjustment means adjusts a parameter in response to a change in feed grade of the feed slurry stream.
40. The control arrangement of claim 38 wherein the adjustment means adjusts a plurality of parameter in response to a change in feed grade of the feed slurry stream.
41. The control arrangement of any one of claims 25 to 40 wherein the mathematical model includes a variable for the efficiency of the separation process.
42. The control arrangement of any one of claims 25 to 41 wherein the mathematical model includes a function of the form
^V,/ = RM where
Rvt is the recovery of valuable mineral in the final recovery zone RM is the mass recovery; and the function α is a function of a plurality of slurry stream parameters.
43. The control arrangement of claim 42 wherein the function for α is predetermined.
44. The control arrangement of claim 43 wherein the function for α has been predetermined by means of polynomial regression by means of experimental analysis.
45. The control arrangement of any one claims 25 to 44 wherein the measuring means measures a slurry stream parameter of the feed slurry stream.
46. The control arrangement of any one of claims 25 to 45 wherein the measuring means measures a slurry stream parameter of the concentrate slurry stream.
47. The control arrangement of any one of claims 25 to 46 wherein the measuring means measures a slurry stream parameter of the tailings slurry stream.
48. The control arrangement of any one of claims 25 to 47 wherein the adjustment means comprises any one or a combination of the apparatus selected from the group consisting of apparatus for recycling a product stream into a feed stream, fluid addition means, dewatering apparatus, apparatus for changing the number of spirals, apparatus for splitting the feed to the spiral separator, any apparatus suitable for achieving a variation in a slurry stream parameter and apparatus for changing particle size distribution of the slurry stream.
49. The control arrangement of claim 48 wherein the apparatus for changing the particle size distribution is a cyclone.
50. The control arrangement of claim 48 wherein the fluid addition means comprises apparatus for the addition of fluid to the system, the fluid being any one of the group consisting of dilution water, slurry and any combination thereof.
51. The control arrangement of any one of claims 25 to 50 wherein the 5 control arrangement is automated.
52. The control arrangement of any one of claims 25 to 51 wherein the control arrangement is operated by means of a feedback loop.
o 53. The control arrangement of any one of claims 25 to 51 wherein the control arrangement is operated by means of a feed forward loop
54. The control arrangement of claim 52 or 53 wherein the control arrangement utilizes a predictive model in the control system.
5
55. A method of controlling the separation of a feed slurry stream flowing to a spiral separator into at least a concentrate slurry stream and a tailings slurry stream in a separation process, the method including the steps of: measuring a plurality of slurry stream parameters;
•o calculating how at least one adjustable feed slurry stream parameter may be adjusted so as to increase the efficiency of the separation process; and adjusting a feed slurry stream parameter in response to the result of the calculation.
!5
56. The method of claim 55 including the step of providing a control arrangement according to any one of claims 1 to 54.
57. The method of any one of claims 55 to 56 wherein the calculation is so done in accordance with a mathematical model.
58. The method of any one of claims 55 to 57 wherein a plurality of feed stream parameters are adjusted in response to the measurement of the measured slurry stream parameter.
59. The method of any one of claims 55 to 58 wherein the feed slurry characteristic is adjusted by any one or a combination of the addition of fluid, dewatering the slurry stream, passing the slurry stream through a cyclone, changing the number of spirals, splitting the feed slurry stream to the spiral separator, and/or changing the particle size distribution.
60. The method of claim 59 wherein the fluid added to the feed slurry stream is dilution water.
61. The method of any one of claims 55 to 60 wherein the adjustment of the feed slurry characteristic is accomplished automatically by means of a feedback control system.
62. The method of any one of claims 55 to 60 wherein the adjustment of the feed slurry characteristic is accomplished automatically by means of a feedforward control system.
63. The method of any one of claims 55 to 62 wherein the adjustment of the feed slurry stream is accomplished by carrying out any action selected from the group consisting of recycling either of the concentrate stream or tailing stream into the feed stream; adding fluid; dewatering the feed slurry stream; passing the slurry through a cyclone; increasing or decreasing the number of spirals; splitting the feed slurry stream to the spiral separator; adjusting the particle size within the feed slurry stream; and/or any combination of the above methods.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA200508393 | 2005-10-17 | ||
| ZA2005/08393 | 2005-10-17 |
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| PCT/IB2006/053789 WO2007046050A1 (en) | 2005-10-17 | 2006-10-16 | Spiral separator and control system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104437839A (en) * | 2014-12-24 | 2015-03-25 | 中冶长天国际工程有限责任公司 | Method and device for controlling grading pressure in ore grinding grading process |
| CN104475240A (en) * | 2014-12-24 | 2015-04-01 | 中冶长天国际工程有限责任公司 | Classification pressure control method and classification pressure control device in grinding-classification process |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004041437A1 (en) * | 2002-11-08 | 2004-05-21 | Multotec Process Equipment (Pty) Limited | Spiral separator and control system |
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2006
- 2006-10-16 WO PCT/IB2006/053789 patent/WO2007046050A1/en active Application Filing
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004041437A1 (en) * | 2002-11-08 | 2004-05-21 | Multotec Process Equipment (Pty) Limited | Spiral separator and control system |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104437839A (en) * | 2014-12-24 | 2015-03-25 | 中冶长天国际工程有限责任公司 | Method and device for controlling grading pressure in ore grinding grading process |
| CN104475240A (en) * | 2014-12-24 | 2015-04-01 | 中冶长天国际工程有限责任公司 | Classification pressure control method and classification pressure control device in grinding-classification process |
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