AU2015342731B2

AU2015342731B2 - A train loading system

Info

Publication number: AU2015342731B2
Application number: AU2015342731A
Authority: AU
Inventors: Stuart DUDFIELD; Hamish MACINTOSH; Shane MACKAY; Andrew Arthur Shook; Jonathon ZEELENBERG
Original assignee: Technological Resources Pty Ltd
Current assignee: Technological Resources Pty Ltd
Priority date: 2014-11-05
Filing date: 2015-11-05
Publication date: 2019-09-26
Anticipated expiration: 2035-11-05
Also published as: WO2016070236A1; AU2015342731A1; CA2966648A1; BR112017009318B1; BR112017009318A2; CA2966648C

Abstract

A train loading system for loading material onto cars of a train is disclosed. The system comprises a material chute disposed above a car travel path along which cars to be loaded with material travel during loading, and a slewing conveyor arranged to deliver material to the material chute, the slewing conveyor being controllably slewable in a direction perpendicular to the direction of travel of material on the slewing conveyor. The material chute is arranged such that the direction of delivery of material from the material chute is dependent on the slewing location of the slewing conveyor relative to the material chute. The system also includes a mass measurement device arranged to produce a mass value indicative of the mass of material travelling on the slewing conveyor, and a mass estimator arranged to produce a car mass estimate of the mass of material delivered to each car as the car travels under the chute, the car mass estimate based on the mass value, the slewing position of the slewing conveyor relative to the chute and the position of the car relative to the chute. The system is arranged to communicate the car mass estimate to an operator, and to predict the final mass of material in a car in consideration of immediate slewing of the slewing conveyor from a first position wherein material is delivered to the car to a second position wherein material is delivered to an adjacent car.

Description

A TRAIN LOADING SYSTEM

Field of the Invention

The present invention relates to a train loading system for loading mined material onto a train at a mine operation.

Background of the Invention

It is known to provide a mine operation such as a mine site with a train loading facility arranged to facilitate loading of material onto dedicated material transport trains by train loadout operators.

Typically, the cars of such trains have an associated overload mass limit that for safety reasons should not be exceeded, and train loadout operators are typically responsible for ensuring that the mass of each train car is below the overload limit.

However, the task of ensuring that each car mass is below the overload mass limit is not simple because the material tends to be loaded into the cars at high speed, and the density of the material loaded into the cars is variable. In addition, each car is typically weighed when the car has moved away from the material flow, for example 4 car lengths away. As a consequence, the mass of material in a car can vary significantly and a car overload situation may not be detected until several more cars have been filled.

When a car mass overload is detected, it is necessary to stop the train loading process in order that the excess material in the car can be removed, but this causes undue delays.

In order to reduce the likelihood of stoppages during the train loading process, operators tend to load the train cars conservatively, and while the likelihood of train stoppages is much reduced as a result, a consequence is that at least some of the train cars are loaded significantly under the mass overload limit, and this equates to a significant loss of production.

Summary of the Invention

It will be understood that in the present specification a mine operation means any operation or facility associated with extracting, handling, processing and/or transporting bulk commodities in a resource extraction environment or part of such a process, for example mine sites, rail facilities, port facilities, and associated infrastructure.

In accordance with a first aspect of the present invention, there is provided a train loading system for loading material onto cars of a train, the system comprising:

a material chute disposed above a car travel path along which cars to be loaded with material travel during loading;

a slewing conveyor arranged to deliver material to the material chute, the slewing conveyor being controllably slewable relative to the material chute;

the material chute arranged such that the direction of delivery of material from the material chute is dependent on the slewing location of the slewing conveyor relative to the material chute;

a mass measurement device arranged to produce a mass value indicative of the mass of material travelling on the slewing conveyor; and a mass estimator arranged to produce a car mass estimate of the cumulative mass of material delivered to each car as the car travels under the chute, the car mass estimate based on the mass value, the slewing position of the slewing conveyor relative to the chute and the position of the car relative to the chute;

wherein the system is arranged to communicate the car mass estimate to an operator; and wherein the system is arranged to predict the final mass of material in a car in consideration of immediate slewing of the slewing conveyor from a first position wherein material is delivered to the car to a second position wherein material is delivered to an adjacent car.

In an embodiment, the system is arranged to produce a plurality of consecutive mass values, each mass value indicative of a mass of material on a defined length portion of the slewing conveyor.

In an embodiment, the system is arranged to determine the consecutive mass values that correspond to material added to a car, and the system includes a mass accumulator arranged to add the determined consecutive mass values together so as to produce an estimate of the mass of material added to the car.

In an embodiment, the mass measurement device is disposed a defined distance from an end of the slewing conveyor adjacent the chute, wherein the system is arranged to apply a delay dependent on the defined distance to each mass value produced by the mass estimator, and to use the delayed mass values to estimate the mass of material added to the car.

In an embodiment, the mass measurement device comprises a weightometer.

In an embodiment, the chute includes a first chute portion and a second chute portion, and the system is arranged to determine from a mass of material received at the chute the ratio of mass that is delivered to the first and second chute portions and thereby the proportions of mass delivered to each car disposed under the chute.

In an embodiment, the system is arranged to determine an estimate of time taken for delivery of all material supplied by the slewing conveyor to change between one of the first and second chute portions to the other of the first and second chute portions as the slewing conveyor slews between the first and second chute portions, to use the time estimate to determine the amount of residual material that will be added to the one of the first and second chute portions before the slewing conveyor slews to the other of the first and second chute portions, and to add the determined amount of residual material to the car mass estimate to produce a predicted conveyor slew car mass estimate.

The estimate of time taken for delivery of all material supplied by the slewing conveyor to change between one of the first and second chute portions to the other of the first and second chute portions as the slewing conveyor slews between the first and second chute portions may be based on the time taken for the slewing conveyor to slew to a position located between the first and second chute portions.

In an embodiment, the system is arranged to display the predicted final mass of material in a car in consideration of immediate slewing of the slewing conveyor.

In an embodiment, the system is arranged to predict the final mass of material in a car in consideration of immediate stop of the slewing conveyor.

In an embodiment, the system is arranged to determine an estimate of the length of slewing conveyor that will continue to advance after immediate stop of the slewing conveyor, to use the length estimate to determine the amount of residual material that will be added to the chute before the slewing conveyor stops, and to add the determined amount of residual material to the car mass estimate to produce a predicted conveyor stop car mass estimate.

In an embodiment, the system is arranged to display the predicted final mass of material in a car in consideration of immediate stop of the slewing conveyor.

In an embodiment, the system is arranged to display a car mass estimate graphically, for example as a rectangle of increasing height as the car mass estimate increases. In an embodiment, the display includes a setpoint marker indicative of a target car mass adjacent the graphical car mass estimate.

In an embodiment, the system is arranged to colour code the graphical car mass estimate such that the height of the rectangle relative to the setpoint marker is represented by colour. The colour code may be arranged such that the rectangle is shown in a first colour if the current car mass is more than a defined tolerance above the car mass target, the rectangle is shown in a second colour if the current car mass is within a defined tolerance above and below the car mass target, and the rectangle is shown in a third colour if the current car mass is less than a defined tolerance below the car mass target.

In an embodiment, the system is arranged to display a slew timer indicative of the amount of time available until the slewing conveyor should commence slewing in order for the predicted final mass of material in a car to be substantially equal to a target car mass.

In an embodiment, the slew timer includes a graphical representation of the amount of time available until the slewing conveyor should commence slewing.

2015342731 16 Aug 2019

In an embodiment, the slew timer includes a numerical representation of the amount of time available until the slewing conveyor should commence slewing.

In an embodiment, the slew timer includes a conveyor stop indicator indicative of the time that the conveyor should be stopped in order for the predicted final mass of material in a car to be substantially equal to a target car mass.

In an embodiment, the system is arranged to display the slew timer when the car mass estimate is within a defined weight of the target car mass, such as within 15 tonnes of the target car mass.

In an embodiment, the system is arranged to fix the speed of the slewing conveyor when the estimated car mass value reaches a defined estimated value.

In an embodiment, the system comprises an overload controller arranged to monitor the predicted conveyor stop car mass estimate as the car is loaded with material and to automatically stop the slewing conveyor when the predicted conveyor stop car mass estimate reaches a defined overload car mass.

In an embodiment, the system includes at least one train position sensor arranged to determine the location of a train relative to the train loading system and thereby the locations of cars of the train relative to the chute.

In an embodiment, the system includes a car weigher arranged to measure the mass of a loaded car, and the system is arranged to display measured car mass values on the display.

In an embodiment, the system includes stored car tare mass values, each tare mass value indicative of the tare weight of a particular car, and the system is arranged to determine the actual weight of material loaded into the cars using the measured car mass values and the respective car tare mass values.

In an embodiment, the system is arranged to use the measured car mass values and the corresponding predicted car mass values to produce an error correction value, the error correction value used by the mass estimator to improve the accuracy of the car mass estimate produced by the mass estimator.

In an embodiment, the system is arranged to calculate a variability value indicative of the variability of the measured car mass values. The variability value may be a standard deviation value.

In an embodiment, the system is arranged to use a desired probability value indicative of the probability of occurrence of a car overload and the variability value to calculate a target set point mass indicative of a target car mass.

In an embodiment, the system is arranged to display the target set point mass on the display.

In accordance with a second aspect of the present invention, there is provided a method of loading material onto cars of a train at a mine operation, the method comprising:

providing a material chute disposed above a car travel path along which cars to be loaded with material travel during loading;

delivering material to the material chute on a slewing conveyor, the slewing conveyor being controllably slewable relative to the material chute;

controlling the location of delivery of material to the chute by controlling the slewing location of the slewing conveyor relative to the material chute;

producing a mass value indicative of the mass of material travelling on the slewing conveyor;

producing a car mass estimate of the cumulative mass of material delivered to each car as the car travels under the chute, the car mass estimate based on the mass value, the slewing position of the slewing conveyor relative to the chute and the position of the car relative to the chute;

communicating the car mass estimate to an operator; and predicting the final mass of material in a car in consideration of immediate slewing of the slewing conveyor from a first position wherein material is delivered to the car to a second position wherein material is delivered to an adjacent car.

Brief Description of the Drawings

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic perspective representation of a train loading system according to an embodiment of the present invention;

Figure 2 is a diagrammatic representation of the train loading system shown in Figure 1, with the train loading system shown from a first side;

Figure 3 is a diagrammatic representation of the train loading system shown in Figure 1, with the train loading system shown from a second side;

Figure 4 is a diagrammatic representation of the train loading system shown in Figure 3, with the train loading system shown during use;

Figure 5 is a plot illustrating the relationship between the position of a slewing conveyor speed control device and speed of the slewing conveyor;

Figure 6 is a block diagram of components of a train loading system according to an embodiment of the present invention;

Figure 7 is a block diagram illustrating functional components implemented by the train loading system shown in Figure 6;

Figure 8 shows a plot of estimated current car mass during car loading and predicted final car mass after conveyor slewing or slewing conveyor stop;

Figure 9 is a schematic diagram of an operator display showing car mas estimates diagrammatically and a slew timer;

Figure 10 is a block diagram of a car mass estimator of the functional components shown in Figure 7;

Figure 11 is a plot illustrating the relationship between the slew position of the slewing conveyor and percentage of ore material directed into a first chute portion of a chute of the train loading system;

Figure 12 shows plots of car mass added to a car following immediate slewing conveyor stop or immediate conveyor slewing relative to slewing conveyor speed; and

Figure 13 is a flow diagram illustrating a method of loading a train in accordance with an embodiment of the present invention.

Description of an Embodiment of the Invention

An embodiment of a train loading system will now be described with reference to mine operations in the form of mine sites, although it will be understood that other mine operations wherein train loading operations occur are envisaged.

An example train loading system 10 is shown diagrammatically in Figure 1 and conceptually in Figures 2 to 4.

The train loading system 10 is arranged to load a train 12 with material, in this example ore derived from one or more mine sites.

Each train 12 includes a plurality of cars 14 and at least one, and typically 3, locomotives (not shown). Ore to be disposed in the cars 14 is transported to the train loading system 10 using delivery conveyors 16 that transport the material to a surge bin 18.

The surge bin 18 delivers ore to a feeder conveyor 20 that supplies ore to a slewing conveyor 22 arranged to pivot under operator control about a pivot arrangement 24. The slewing conveyor 22 supplies ore to a chute 26 that directs ore to the cars 14 disposed under the chute 26.

In this example, the pivot arrangement 24 includes a platform 28 provided with wheels 30 that travel in arcuate channels 32, the platform 28 supporting a first end 34 of the slewing conveyor 22. A middle portion 36 of the slewing conveyor 22 rests on a first trolley 38 arranged to facilitate slewing motion of the slewing conveyor 22, and a second end 40 of the slewing conveyor 22 rests on a second trolley 42 also arranged to facilitate slewing motion of the slewing conveyor 22. Movement of the first and second trolleys 38, 42 and thereby slewing movement of the slewing conveyor 22 is controlled in this example using hydraulic cylinders 44.

The second end 40 of the slewing conveyor 22 is mounted above a rail track 46 on a support frame 48 such that ore travelling on the slewing conveyor 22 can be directed by the slewing conveyor 22 into cars 14 of a train travelling on the rail track 46 beneath the support frame 48.

As best shown in Figure 2, a weightometer 50 is provided to weigh ore on the slewing conveyor 22 as the ore is transported on the slewing conveyor 22 to the chute 26. In this example, the weightometer 50 produces a mass value indicative of the mass flow rate of ore that passes over the weightometer 50. In this example, the weightometer 50 is disposed 8.1m from the second end 40 of the slewing conveyor 20.

Using the mass value produced by the weightometer 50 and the speed of the slewing conveyor 22, the train loading system 10 calculates a sequence of estimated mass values indicative of the mass of material that is loaded into the chute 26.

In addition, using the sequence of mass values, information indicative of the location of the train cars 14 relative to the chute 26 and the position of the slewing conveyor 22 relative to the chute 26, the train loading system 10 calculates an estimate of the mass of ore that is loaded into each car 14.

As best shown in Figure 3, a train 12 arriving at the train loading system 10 travels along the rail track 46 such that cars 14 of the train 52 pass under the chute 26 and in this way receive ore through the chute 26 from the slewing conveyor 22.

The chute 26 includes first and second chute portions 54, 56 and a cross-saddle 58. By controlling the position of the second end 40 of the slewing conveyor 22 and the speed of the slewing conveyor 22, it is possible for an operator to control the amount of ore directed to the first and second chute portions 54, 56 as the train moves slowly through the train loading system 10 in the direction of arrow 60. In this way, the operator is able to continuously fill the cars 14 without stopping the slewing conveyor 22 by appropriate movement of the second end 40 of the slewing conveyor 22.

For example, as shown in Figures 3 and 4, as the train 12 arrives at the train loading system 10, a first car 14a moves to a position under the first chute portion 54. In response, the operator positions the second end 40 of the slewing conveyor 22 such that the second end 40 is disposed over the first chute portion 54. As a consequence, all of the ore from the slewing conveyor 22 is directed to the first chute portion 54 and thereby into the first car 14a disposed under the first chute portion 54.

As the train 12 moves in the direction of the arrow 60, the operator moves the second end 40 of the slewing conveyor 22 so as to distribute ore in the car 14a, and at an appropriate time slews the slewing conveyor 22 between the first and second chute portions 54, 56 so as to control the amount of ore loaded into a car, maintain the amount of ore less than or equal to a target weight of ore, and begin loading ore into an adjacent second car 14b.

The operator controls the position of the slewing conveyor 22 in this way based on past experience and previous car masses measured by the car weigher. If previous car masses have been relatively high, and especially if a significant number of overloads have occurred, the tendency of the operator is to be cautious and fill the cars at a relatively low level. Typically, a car weigher is provided at least 4 cars ahead to weigh each loaded car 14.

As shown in Figures 3 and 4, the train loading system 10 also includes train position sensors 59 arranged to provide direction information indicative of the direction of travel of the train 12 and location information indicative of the position of the train 12 relative to the train loading system 10, and thereby the positions of the cars 14 relative to the chute 26.

In this example, the speed of the slewing conveyor 22 is controllable with the feeder conveyor 20 using a slewing conveyor speed control device 68 such that the speed of the feeder conveyor 20 matches the speed of the slewing conveyor 22 and the speed of both conveyors is controlled at the same time by an operator. The slewing conveyor speed control device 68 may for example include a joystick. The slewing conveyor 22 is arranged to start before the feeder conveyor 20, although this creates an ore gap at start-up.

In this example, the slewing position of the slewing conveyor 22 relative to the chute 26 is controllable by an operator using a slew control device 70 that may for example include a joystick.

Figure 5 shows the relationship between the position 69 of a slewing conveyor speed control device 68 and the speed 71 of the slewing conveyor 22. In this example, the minimum speed of the slewing conveyor is 3.4m/s and the speed does not increase until the joystick is set to a position corresponding to about 50% of the range of movement of the joystick. The maximum slewing conveyor speed in this example is 5m/s.

Referring to Figure 6, a block diagram illustrating components 60 of the train loading system 10 is shown. The train loading system components 60 include a control unit 62 for controlling and coordinating operations in the train loading system 10, and a display 64 for displaying train loading information to an operator during a train loading operation.

The control unit 62 may include associated data storage 63 and memory necessary for storing data and/or programs usable by the control unit 62 to implement desired functionality. In this example, the control unit 62 is arranged to store car mass values produced by the car weigher 66, and calculate a mass variability value indicative of the variability of the measured car mass values, in this example in the form of a standard deviation of the measured car mass values; to calculate current estimated mass values for each car 14 based on the conveyor weightometer 50, conveyor speed, positions of the cars 14 relative to the chute 26, and slewing position of the slewing conveyor 22 relative to the chute 26; to calculate and/or store a target set point indicative of a suggested target car mass; to calculate predicted mass values for each car 14 based on immediate slewing conveyor stop and immediate slewing of the slewing conveyor 22; to calculate when an operator should commence slewing the slewing conveyor or should stop the slewing conveyor 22 in order to achieve a final car mass close to the target car mass; and to control display of train loading information on the display 64.

The target set point may be defined by a user or may be calculated, for example such that the target set point is indicative of a suggested target car mass that a train loading operator should aim for in order to maintain an overload probability at a defined level, for example 0.01, whilst achieving a relatively high car mass.

Functional components 80 implemented by the train loading system, in this example using the control unit 62, are shown in Figure 7. The functional components 80 include a car mass estimator 82 arranged to calculate the estimated current mass value for each car 14 during loading based on the conveyor weightometer 50, the train position sensors 59 and the position of the slewing conveyor 22 according to the operator slew control 70; a car mass predictor 84 arranged to calculate the estimated final mass value for each car 14 based on immediate slewing of the slewing conveyor 22 by an operator, and the estimated final mass value based on immediate slewing conveyor stop; a target set point estimator 86 arranged to calculate a target set point indicative of a suggested average car mass that a train loading operator should aim for in order to maintain an overload probability at a defined level; and a data plotter 88 arranged to control display of the train loading information on the display 64.

The functional components 80 also include a conveyor slew/stop time calculator 91 arranged to calculate when the operator should commence slewing the slewing conveyor 22 or should stop the slewing conveyor 22 in order that the final car mass weight is at or close to the target car mass. The conveyor slew/stop time calculator 91 also calculates slew timer information indicative of a countdown representing the amount of time until the operator should commence slewing.

The slew countdown and the information indicative of when the operator should stop the slewing conveyor 22 in order to obtain the target car mass is shown to the operator on the display 64.

It will be appreciated that the variability of the actual measured car mass values, in this example represented by the standard deviation, has a significant effect on the probability of occurrence of an overload. This is because a larger standard deviation corresponds to a greater variation of car mass values, and therefore for a given average car mass value more car mass values above the overload mass level. It therefore follows that for car mass values that have a relatively large standard deviation, the desired average car mass, that is the target car mass, should be reduced in order that the likely number of car mass values above the overload mass is maintained relatively low, and for car mass values that have a relatively small standard deviation, the desired average car mass, that is the target car mass, should be increased in order that a more optimum level of material is loaded into a car whilst still maintaining the likely number of car mass values above the overload mass relatively low. Accordingly, by appropriately selecting the target car mass in view of the standard deviation of recent car mass values, the mass of material loaded into a train can be increased without unduly affecting the probability of train overloads.

Railcar masses tend to approximate a normal distribution, and as such a 1% probability of exceeding a defined value occurs at a value equal to the mean value of the mass values plus 2.33o, where o is the standard deviation of the mass values. Accordingly, for mass values that have high variability, the average railcar mass must be lower than for mass values that have low variability, in order to maintain the same 1% probability of overload. By calculating the standard deviation of the measured car mass values, and defining a desired probability that corresponds to a defined overload mass, an average mass value can be calculated that is appropriate to use as the target mass value.

The functional components 80 also include an overload controller 90, in this example also implemented by the control unit 62. However, as an alternative it will be understood that the overload controller 90 may be implemented by a component separate to the control unit 62.

In Figure 8, a graph 92 including estimated current car mass values 94, and predicted final car mass values after conveyor slewing 96 or slewing conveyor stop 98 is shown, and this information is displayed to an operator during a car loading operation. The graph 92 represents estimated current car mass values 94 and predicted final car mass values 96, 98 when the slewing conveyor speed is about 5m/s.

The graph 92 also shows a slew position plot 100 indicative of the slewing position of the slewing conveyor 22 and the relationship between the position of the slewing conveyor 22 and the predicted final car mass after conveyor slewing.

It will be appreciated that the predicted final mass values plots 96, 98 are 4 cars ahead of the actual car mass values measured by the car weigher 66.

Using the graph 92, an operator is able to determine when to begin slewing the slewing conveyor 22 in order to transition ore delivery to an adjacent car 14 of the train 12 whilst achieving a predicted final car mass for a previous car 14 that is close to the defined target mass.

In addition to displaying to an operator the estimated current car mass 94 and predicted final car mass values 96, 98, the actual car masses determined by the car

2015342731 16 Aug 2019 weigher 66 may also be displayed so that the operator is provided with an indication of the accuracy of the car mass estimator 82 and the car mass predictor 84.

In an alternative embodiment, the estimated car mass values 94 are displayed to an operator diagrammatically and a visual indicator is shown to the operator to indicate to the operator when to commence slewing of the slewing conveyor 22 or to stop the slewing conveyor 22 in order to obtain a final predicated car mass at or close to the target car mass.

io An example screen displayed to an operator during a car loading operation is shown in Figure 9.

Figure 9 shows schematic representations 101a, 101b, 101c, 101d of rail cars 14, and a schematic representation 102 of the chute 26 with a triangular icon 103 representing 15 the cross-saddle 58 of the chute 26 and a square icon 104 representing the slewing conveyor 22. Each representation 101 of a rail car 14 includes a first marker 105 indicative of a defined car mass, in this example 100 tonnes, and a setpoint marker 106 indicative of the defined target car mas, in this example 116 tonnes. Each representation 101 of a rail car 14 also includes a current mass indicator, in this example in the form of a coloured box 107, the height of which represents the estimated current mass in the relevant car 14. For example, in the example shown in Figure 9, a first car 14a shown by representation 101a has an estimated car mass slightly above the target car mass; a second car 14b shown by representation 101b has an estimated car mass between 100 tonnes and the target car mas; and third and fourth cars 14c, 14d shown by representations 101c and 101 d have not yet received material and so contain zero tonnes of material.

It will be appreciated that the square icon 104 representing the slewing conveyor 22 is shown above the second car 14b indicated by representation 101b because the second car 14b is currently being filled by the slewing conveyor.

The current mass indicators 107 may be shown differently, for example colour coded, depending on whether the current estimated mass of material in a car is more than a defined tolerance above the target car mass, is within a defined tolerance above and 35 below the target car mass, or the estimated mass of material in a car is less than a

2015342731 16 Aug 2019 defined tolerance below the target car mass. Each current mass indicator 107 may also include a numerical estimated car mass 108 and a car number 109.

In this example, the display also shows a target mass selector 111 that is controllable by an operator to define the target mass of a car.

In this example, the display also shows a slew timer 113 that provides a user with assistance in relation to when to begin slewing the slewing conveyor 22 away from the car currently receiving material. The slew timer 113 provides the operator with a io numerical 115 and visual 117 countdown to commencement of slewing, and in this example the slew timer represents the final 15 tonnes to be loaded into a car in order for the car to reach the target car mass.

In this example, therefore, the numerical countdown 115 counts down from 15 to zero, 15 and a marker line 119 of the visual countdown continuously moves towards a zero line

121.

The slew timer 113 also includes a conveyor stop indicator 123 that represents the latest time that the conveyor can be stopped in order to maintain the car mass below 20 overload. Accordingly, if slewing the slewing conveyor is not possible, then in order to prevent overload the slewing conveyor 22 must be stopped before the marker line 119 reaches the conveyor stop indicator 123.

In this embodiment, the system is arranged to display the slew timer 113 only when the 25 current estimated car mass is within 15 tonnes of the target car mass.

During use, an operator uses the slew timer 113 to determine when to commence slewing the slewing conveyor 22 or when to stop the slewing conveyor 22. In either situation, the final car mass is expected to be close to the target car mass.

The slew timer 113 may be arranged to change appearance depending on the relative position of the marker line 119, for example such that the visual countdown indicator 117 is shown in a first colour, such as blue, when the marker line 119 is above the conveyor stop indicator 123, the visual countdown indicator 117 is shown in a second 35 colour, such as yellow, when the marker line 119 is within the conveyor stop indicator

2015342731 16 Aug 2019

123 but above a position corresponding to about 0.5 tonnes remaining until suggested commencement of slewing, and the visual countdown indicator 117 is shown in a third colour, such as green, when the marker line 119 is past a position corresponding to about 0.5 tonnes remaining until suggested commencement of slewing.

Functional components 110 of the car mass estimator 82 are shown in Figure 10.

In this example, the functional components 110 include a conveyor model 112 arranged to calculate a mass value indicative of the mass that is added to the chute 26 io for a defined length portion of the slewing conveyor 22. In this way, the weight of ore travelling on the slewing conveyor 22 is discretized by conveyor length and an estimate can be obtained for the weight of ore that is added to the chute 26 for each of the discrete portions of the slewing conveyor 22. For this purpose, the conveyor model 112 uses mass flow rate data 114 provided by the weightometer 50 and the speed 116 15 of the slewing conveyor 22. The defined length portion of the slewing conveyor 22 is based on a defined time period (dt) as follows:

beltAdvance = dtx speed where ‘beltAdvance’ is the defined length portion of the slewing conveyor and ‘speed’ is the speed of the slewing conveyor.

An estimate for the mass of ore on the defined length portion of the slewing conveyor 22 is given by:

tonnesPastWeigher = dt*flowRate(tps) *flowGain where ‘tonnesPastWeigher’ is the estimate for the mass of ore on a defined length portion ‘beltAdvance’ of the slewing conveyor, ‘flowRate(tps)’ is the mass flow rate provided by the weightometer 50, and flowGain’ is an error correction multiplier discussed in more detail below.

Using the estimate ‘tonnesPastWeigher’ for the mass of ore on a defined length portion of the slewing conveyor 22, the length of the slewing conveyor 22 between the weightometer 50 and the second end 40 of the slewing conveyor 22 above the chute

26, the defined length portion ‘beltAdvance’ of the slewing conveyor, and the speed of the slewing conveyor, the conveyor model 122 calculates an estimate for the mass of ore directed to the chute 22 by effectively applying a delay to the discretized mass estimates calculated as the ore passes over the weightometer 50.

The functional components 110 also include a chute model 118 arranged to calculate the relative proportions of the calculated mass estimate that are supplied to the first and second chute portions 54, 56 based on the current slew position 120 of the slewing conveyor 22 relative to the chute 26.

The location of the slewing conveyor 22 relative to the chute 26 is defined as a slew position percentage such that the slew position percentage below which all ore is directed to the second chute portion 56 is ‘SLEW_RIGHT_LIMIT’, and the slew position percentage above which all ore is directed to the first chute portion 54 is ‘SLEW_LEFT_LIMIT’.

The mass estimate of ore is assigned proportionally to the first and second chute portions 54, 56 according to:

ratio = s/ewPosition - SLEW RIGHT LIMIT

SLEW_LEFT_LIMIT - SLEW_RIGHT_LIMIT where ‘ratio’ is the proportion of the mass estimate of ore assigned to the first chute portion 54, and ‘slewPosition’ is the current slew position percentage.

In this example, the SLEW_RIGHT_LIMIT is 34% and the SLEW_LEFT_LIMIT is 59%, although it will be understood that other slew percentage values are envisaged.

A plot 109 illustrating the relationship between slew position percentage and percentage of mass directed to the first chute portion 54 is shown in Figure 11.

The functional components 110 also include a car mass accumulator 122 arranged to store an array of mass estimate values indicative of the respective discretized mass estimates for the consecutive defined length portions of the slewing conveyor 22. The car mass accumulator 122 is also arranged to calculate cumulative mass values for each of the cars 14 using the proportionate mass values provided by the chute model 118, the locations of the cars 14 determined using the car location sensors 59 and the tare weight of the cars 14.

In this example, in order to improve accuracy of the car mass estimates, the tare weights of the cars 14 are obtained from a tare weight database 124 that stores tare weights for each individual car 14. Alternatively, a reference tare weight, such as 21.5 tonnes, may be used for each car 14.

The functional components 110 also include a car mass predictor 126 arranged to predict the final mass of ore in a car 14 in the event of immediate slewing 128 of the slewing conveyor 22, and to predict the final mass of ore in a car 14 based on immediate stop 130 of the slewing conveyor 22. The final mass predictions are used to assist the operator in deciding when to begin to slew the slewing conveyor 22 in order to maintain the full weight of the car 14 as close as possible to the target weight, and for example by the overload controller 90 to determine when to cause immediate stop of the slewing conveyor 22 in order to avoid car overload.

The final mass prediction based on immediate slewing 128 of the slewing conveyor 22 requires a constant slewing conveyor speed and a constant slewing speed. After commencement of slewing, for a car 14 that is receiving ore, the time remaining until ore is no longer delivered to the car 14 is given by:

Time remaining t(s) = slew distance from centre slew velocity where the ‘slew distance from centre’ is the slew position percentage difference from the centre (which corresponds to a slew percentage of 50%); that is 50% - the current slew position percentage.

In this example, the slew velocity is defined as 15% per second.

It will be appreciated that for this calculation it is assumed for simplicity that for a slew percentage less than 50%, all ore flows into the second chute 56, and for a slew percentage greater than 50%, all ore flows into the first chute 54.

The length of belt advance during this time is given by:

d = t * current belt speed

In order to provide an estimate for the final mass in the car after slewing, the car mass predictor 126 adds the current estimate for the mass of ore in a car 14 to the calculated discretized mass estimates of ore still on the slewing conveyor 22 and that will be delivered to the car 14 by the slewing conveyor 22 in the calculated time period t. If the belt advance distance d is longer than the distance between the weightometer 50 and the second end of the slewing conveyor 22, the car mass predictor 126 adds extra weight to the final mass estimate value based on the difference between d and the distance between the weightometer 50 and the second end of the slewing conveyor 22 using the current tonnes/m flow rate at the weightometer 50.

The final mass prediction based on immediate stop 130 of the slewing conveyor 22 is calculated by first determining the length of slewing conveyor advance d during the time taken for the slewing conveyor 22 to stop:

d = v²/2a + Lv where v is the current slewing conveyor speed, a is the deceleration of the slewing conveyor 22 (assumed in this example to be 1.3m/s²), and L is a constant that represents a delay between a conveyor stop command and conveyor motor response (assumed to be 1s).

The final mass prediction is then calculated based on the calculated value for the length of slewing conveyor advance d using the methodology discussed above in relation to the final mass prediction after immediate slewing.

The current mass value 94 and the final mass values after immediate slewing 96 and after immediate conveyor stop 98 are shown on the display 64, for example in a form as shown in Figure 9.

It will be appreciated that information displayed to the operator enables an operator to make an informed decision as to when to begin slewing the slewing conveyor 22 or when to stop the slewing conveyor 22 in order to achieve a final car mass that is close to the target car mass.

It will also be appreciated that the displayed final mass value after immediate conveyor stop 98 may be used by the overload controller 90 to automatically stop the slewing conveyor when a car overload is likely to occur.

An error is typically present between the actual car mass measured by the car weigher 66 and the predicted final car mass calculated by the car mass predictor 126 based on the measurements produced by the weightometer 50. In order to minimise this, the difference between recently estimated and measured car mass values 132 is calculated by a weightometer correction module 134 that receives the measured car mass values 132 and the predicted values produced by the car mass predictor 126 and supplies a mass correction value to the conveyor model 112.

The error is given by:

error = (trackscaleTonnes[j-n:j] massEstimatorTonnes[j-n:j])/n and weightometerGain = 1 + Ki * error where j is the last car number weighed by the track scales, n is the number of cars to be used for the integration (for example 10), and Ki is the integral term for control (for example Ki = 0.003).

The overload controller 90 is arranged to override operator control by automatically causing the slewing conveyor 22 to stop when an overload condition is predicted.

In the present example, the overload controller 90 has three setpoints.

A first setpoint ‘conveyor slowdown setpoint’ defines the estimated car mass value at which the speed of the conveyor is set to a fixed conveyor speed that can not be modified by the operator. This is necessary because the car mass prediction by slew 128 and the car mass prediction by conveyor stop 130 are dependent on a constant slewing conveyor speed.

A second setpoint ‘target setpoint’ defines the target car mass to be loaded into each car.

A third setpoint Overload controller setpoint’ defines the upper limit of car mass allowed in a car. When the predicted final mass in a car is estimated to reach the overload controller setpoint, the overload controller 90 deactivates the slewing conveyor 22.

The accuracy of the car mass estimator 82 will determine how close the overload controller setpoint can be to the maximum allowable car weight. For a mass estimator with a standard deviation error of 1.5 tonnes and a maximum allowable car weight of 123 tonnes, the overload controller setpoint would need to be set at a value of about 119.5 tonnes in order to achieve an overload rate of about 1% wherein the overload controller is triggered.

It will be appreciated that by providing an overload controller 90 arranged to intervene if a car is expected to overload, in effect the normal distribution of loaded car masses centered around the target car mass is skewed towards higher car masses whilst providing a very low probability of occurrence of an overloaded car. In other words, providing an overload controller has the effect of automatically increasing the target car mass if the overload controller is successful because preventing car overloads from occurring has the effect of causing the standard deviation to reduce.

It will also be appreciated that providing an overload controller 90 provides a high probability that the train loading system will fail well in that car overloads are prevented from occurring even if the decision made by the operator in relation to when to commence slewing the slewing conveyor 22 is incorrect, because in an overload situation the slewing conveyor 20 will be deactivated by the overload controller 90 before a car overload actually occurs.

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It will also be appreciated that although actual car masses are not known until 4 cars later, by providing and displaying estimated car masses useful loading information can be communicated to the operator which can be used by the operator when making decisions in relation to loading of subsequent cars. The displayed loading information and in particular the overload controller 90 are particularly useful for loading the first 4 cars because no historical actual mass data is available.

At least the control unit 62 may be implemented using appropriate hardware, for io example a personal computing type architecture or using a programmable logic controller (PLC).

It will be understood that the timing of deactivation of the slewing conveyor 22 is related to the speed of the slewing conveyor 22 in that the faster the slewing conveyor speed, the earlier the automatic activation of slewing conveyor stop needs to be in order to prevent the final car mass from exceeding the overload controller setpoint. Likewise, increasing the conveyor speed also has the consequence that the operator is required to commence slewing the conveyor earlier in order to not exceed the target car mass.

Figure 12 shows plots of the amount of mass added to a car following immediate slewing conveyor stop 130 or immediate conveyor slewing 132 relative to slewing conveyor speed. With the slewing conveyor speed at 5m/s, the overload controller 90 would need to deactivate the slewing conveyor 22 when the current estimated mass is 25 9 tonnes below the overload controller setpoint. However, this is significantly earlier than when the operator needs to begin slewing the slewing conveyor 22 in order to not exceed the target car mass, and problems are likely to occur as a result. For example, since the slewing conveyor 22 would have already commenced slowing down when the operator begins to slew the slewing conveyor 22, the final car mass after slewing would be less than the predicted final car mass and the car would be under loaded. In addition, the slewing conveyor 22 would have been stopped unnecessarily, causing an ore gap on start up for the next car.

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As can be seen in Figure 12, at slower speeds the above problems are much less pronounced because the difference between the mass added to a car 14 after conveyor stop or slewing of the slewing conveyor 22 is much less.

In order to minimize excessive triggering of the overload controller 90, the target setpoint should be set to a value lower than the overload controller setpoint minus the amount of additional tonnes that are delivered by immediate slewing conveyor stop. For example, at a slewing conveyor speed of 3.4m/s, the amount of additional tonnes added in response to immediate conveyor stop is about 4.5 tonnes, and for an io overload controller setpoint of 119.5 tonnes, the target setpoint would be set at about 115 tonnes.

Further improvements would be achieved by reducing the slewing conveyor speed, for example to about 2m/s, which would cause an increase in the target setpoint to about 15 117 tonnes.

Alternatively, the overload controller may be arranged to not stop the slewing conveyor if the predicted final mass after immediate slewing is lower than the overload controller setpoint.

A flow diagram 140 illustrating steps 142 to 156 of an example method of loading a train is shown in Figure 13.

During use, when a train 12 arrives 142 at the train loading facility, the train 12 is caused to move slowly relative to the train loading system 10 so that ore can be controllably loaded onto cars 14 of the train 12.

As the cars arrive under the chute 26, the operator monitors the cars 14 and manually controls 144 the speed of the slewing conveyor 22 and the position of the slewing conveyor in order to load a first car 14 of the train 12. The system calculates and displays car mass estimate values 146, and when the estimated car mass reaches a conveyor slowdown setpoint, the system 10 fixes the speed 148 of the slewing conveyor 22. When the remaining tonnes to load into the car in order for the car to reach the target car mass is 15 tonnes, the system displays the slew timer 150, 152.

The operator views 154 the displayed estimated current mass of the car and the slew

2015342731 16 Aug 2019 timer on the display, and if the slew timer reaches zero 160, the operator instigates slewing 162 of the slewing conveyor 22. If the prediction of final mass in the car in consideration of immediate conveyor stop reaches 156 the overload controller setpoint, then the overload controller 90 instigates 158 immediate conveyor stop. This process continues for each car 14 of the train 12.

When the cars reach the car weigher 28, the actual mass of material in the cars is measured and stored and a variability value, in this example a standard deviation, may be calculated based on the measured car mass values and the predicted car mass io values. The variability value may be used with a defined overload probability value to calculate the target mass set point indicative of a suggested average car mass that a train loading operator should aim for.

Modifications and variations as would be apparent to a skilled addressee are deemed 15 to be within the scope of the present invention.

Claims

CLAIMS:

1. A train loading system for loading material onto cars of a train, the system comprising:

a material chute disposed above a car travel path along which cars to be loaded with material travel during loading;

a slewing conveyor arranged to deliver material to the material chute, the slewing conveyor being controllably slewable relative to the material chute;

the material chute arranged such that the direction of delivery of material from the material chute is dependent on the slewing location of the slewing conveyor relative to the material chute;

a mass measurement device arranged to produce a mass value indicative of the mass of material travelling on the slewing conveyor; and a mass estimator arranged to produce a car mass estimate of the cumulative mass of material delivered to each car as the car travels under the chute, the car mass estimate based on the mass value, the slewing position of the slewing conveyor relative to the chute and the position of the car relative to the chute;

wherein the system is arranged to communicate the car mass estimate to an operator; and wherein the system is arranged to predict the final mass of material in a car in consideration of immediate slewing of the slewing conveyor from a first position wherein material is delivered to the car to a second position wherein material is delivered to an adjacent car.
2. A train loading system as claimed in claim 1, wherein the system is arranged to produce a plurality of consecutive mass values, each mass value indicative of a mass of material on a defined length portion of the slewing conveyor.
3. A train loading system as claimed in claim 2, wherein the system is arranged to determine the consecutive mass values that correspond to material added to a car, and the system includes a mass accumulator arranged to add the determined consecutive mass values together so as to produce the estimate of the cumulative mass of material added to the car.
4. A train loading system as claimed in any one of claims 1 to 3, wherein the mass measurement device is disposed a defined distance from an end of the slewing conveyor adjacent the chute, and the system is arranged to apply a delay dependent on the defined distance to each mass value produced by the mass estimator, and to use the delayed mass values to estimate the cumulative mass of material added to the car.
5. A train loading system as claimed in any one of the preceding claims, wherein the mass measurement device comprises a weightometer.
6. A train loading system as claimed in any one of the preceding claims, wherein the chute includes a first chute portion and a second chute portion, and the system is arranged to determine from a mass of material received at the chute the ratio of mass that is delivered to the first and second chute portions and thereby the proportions of mass delivered to each car disposed under the chute.
7. A train loading system as claimed in claim 6, wherein the system is arranged to determine an estimate of time taken for delivery of all material supplied by the slewing conveyor to change between one of the first and second chute portions to the other of the first and second chute portions as the slewing conveyor slews between the first and second chute portions, to use the time estimate to determine the amount of residual material that will be added to the one of the first and second chute portions before the slewing conveyor slews to the other of the first and second chute portions, and to add the determined amount of residual material to the car mass estimate to produce a predicted conveyor slew car mass estimate.
8. A train loading system as claimed in claim 7, wherein the estimate of time taken for delivery of all material supplied by the slewing conveyor to change between one of the first and second chute portions to the other of the first and second chute portions as the slewing conveyor slews between the first and second chute portions is based on the time taken for the slewing conveyor to slew to a position located between the first and second chute portions.
9. A train loading system as claimed in claim 7 or claim 8, wherein the system is arranged to display the predicted final mass of material in a car in consideration of immediate slewing of the slewing conveyor.
10. A train loading system as claimed in any one of the preceding claims, wherein the system is arranged to predict the final mass of material in a car in consideration of immediate stop of the slewing conveyor.
11. A train loading system as claimed in claim 10, wherein the system is arranged to determine an estimate of the length of slewing conveyor that will continue to advance after immediate stop of the slewing conveyor, to use the length estimate to determine the amount of residual material that will be added to the chute before the slewing conveyor stops, and to add the determined amount of residual material to the car mass estimate to produce a predicted conveyor stop car mass estimate.
12. A train loading system as claimed in claim 10 or claim 11, wherein the system is arranged to display the predicted final mass of material in a car in consideration of immediate stop of the slewing conveyor.
13. A train loading system as claimed in any one of the preceding claims, wherein the system is arranged to display a car mass estimate graphically.
14. A train loading system as claimed in claim 13, wherein the system is arranged to display a car mass estimate as a rectangle of increasing height as the car mass estimate increases.
15. A train loading system as claimed in claim 14, wherein the display includes a setpoint marker indicative of a target car mass adjacent the graphical car mass estimate.
16. A train loading system as claimed in claim 14 or claim 15, wherein the system is arranged to colour code the graphical car mass estimate such that the height of the rectangle relative to the setpoint marker is represented by colour.

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17. A train loading system as claimed in claim 16, wherein the colour code is arranged such that the rectangle is shown in a first colour if the current car mass is more than a defined tolerance above a car mass target, the rectangle is shown in a second colour if the current car mass is within a defined tolerance above and below the

5 car mass target, and the rectangle is shown in a third colour if the current car mass is less than a defined tolerance below the car mass target.
18. A train loading system as claimed in any one of the preceding claims, wherein the system is arranged to display a slew timer indicative of the amount of time io available until the slewing conveyor should commence slewing in order for a predicted final mass of material in a car to be substantially equal to a target car mass.
19. A train loading system as claimed in claim 18, wherein the slew timer includes a graphical representation of the amount of time available until the slewing conveyor

15 should commence slewing.
20. A train loading system as claimed in claim 18 or claim 19, wherein the slew timer includes a numerical representation of the amount of time available until the slewing conveyor should commence slewing.
21. A train loading system as claimed in any one of claim 18 to 20, wherein the slew timer includes a conveyor stop indicator indicative of the time that the conveyor should be stopped in order for the predicted final mass of material in a car to be substantially equal to a target car mass.
22. A train loading system as claimed in any one of claims 18 to 21, wherein the system is arranged to display the slew timer when the car mass estimate is within a defined weight of the target car mass.

30
23. A train loading system as claimed in claim 22, wherein the system is arranged to display the slew timer when the car mass estimate is within 15 tonnes of the target car mass.
24. A train loading system as claimed in any one of the preceding claims, wherein the system is arranged to fix the speed of the slewing conveyor when the estimated car mass value reaches a defined estimated value.
25. A train loading system as claimed in any one of the preceding claims, wherein the system comprises an overload controller arranged to monitor the predicted conveyor stop car mass estimate as the car is loaded with material and to automatically stop the slewing conveyor when the predicted conveyor stop car mass estimate reaches a defined overload car mass.
26. A train loading system as claimed in any one of the preceding claims, wherein the system includes at least one train position sensor arranged to determine the location of a train relative to the train loading system and thereby the locations of cars of the train relative to the chute.
27. A train loading system as claimed in any one of the preceding claims, wherein the system includes a car weigher arranged to measure the mass of a loaded car, and the system is arranged to display measured car mass values on the display.
28. A train loading system as claimed in claim 27, wherein the system includes stored car tare mass values, each tare mass value indicative of the tare weight of a particular car, and the system is arranged to determine the actual weight of material loaded into the cars using the measured car mass values and the respective car tare mass values.
29. A train loading system as claimed in claim 27 or claim 28, wherein the system is arranged to use the measured car mass values and the corresponding predicted car mass values to produce an error correction value, the error correction value used by the mass estimator to improve the accuracy of the car mass estimate produced by the mass estimator.
30. A train loading system as claimed in any one of claims 27 to 29, wherein the system is arranged to calculate a variability value indicative of the variability of the measured car mass values.
31. A train loading system as claimed in claim 30, wherein the variability value is a standard deviation value.
32. A train loading system as claimed in claim 30 or claim 31, wherein the system is arranged to use a desired probability value indicative of the probability of occurrence of a car overload and the variability value to calculate a target set point mass indicative of a target car mass.
33. A train loading system as claimed in claim 32, wherein the system is arranged to display the target set point mass on the display.
34. A method of loading material onto cars of a train at a mine operation, the method comprising:

providing a material chute disposed above a car travel path along which cars to be loaded with material travel during loading;

delivering material to the material chute on a slewing conveyor, the slewing conveyor being controllably slewable relative to the material chute;

controlling the location of delivery of material to the chute by controlling the slewing location of the slewing conveyor relative to the material chute;

producing a mass value indicative of the mass of material travelling on the slewing conveyor;

producing a car mass estimate of the cumulative mass of material delivered to each car as the car travels under the chute, the car mass estimate based on the mass value, the slewing position of the slewing conveyor relative to the chute and the position of the car relative to the chute;

communicating the car mass estimate to an operator; and predicting the final mass of material in a car in consideration of immediate slewing of the slewing conveyor from a first position wherein material is delivered to the car to a second position wherein material is delivered to an adjacent car.
35. A method as claimed in claim 34, comprising producing a plurality of consecutive mass values, each mass value indicative of a mass of material on a defined length portion of the slewing conveyor.

2015342731 16 Aug 2019
36. A method as claimed in claim 35, comprising determining the consecutive mass values that correspond to material added to a car, and adding the determined consecutive mass values together so as to produce the estimate of the cumulative mass of material added to the car.
37. A method as claimed in any one of claims 34 to 36, comprising providing a mass measurement device arranged to produce a mass value indicative of the mass of material travelling on the slewing conveyor, disposing the mass measurement device a defined distance from an end of the slewing conveyor adjacent the chute, applying a io delay dependent on the defined distance to each mass value produced by the mass estimator, and using the delayed mass values to estimate the cumulative mass of material added to the car.
38. A method as claimed in any one of the preceding claims, wherein the chute

15 includes a first chute portion and a second chute portion, and the method comprises determining from a mass of material received at the chute the ratio of mass that is delivered to the first and second chute portions and thereby the proportions of mass delivered to each car disposed under the chute.

20
39. A method as claimed in claim 38, comprising determining an estimate of time taken for delivery of all material supplied by the slewing conveyor to change between one of the first and second chute portions to the other of the first and second chute portions as the slewing conveyor slews between the first and second chute portions, using the time estimate to determine the amount of residual material that will be added

25 to the one of the first and second chute portions before the slewing conveyor slews to the other of the first and second chute portions, and adding the determined amount of residual material to the car mass estimate to produce a predicted conveyor slew car mass estimate.

30
40. A method as claimed in claim 39, wherein the estimate of time taken for delivery of all material supplied by the slewing conveyor to change between one of the first and second chute portions to the other of the first and second chute portions as the slewing conveyor slews between the first and second chute portions is based on the time taken for the slewing conveyor to slew to a position located between the first

35 and second chute portions.

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41. A method as claimed in claim 39 or claim 40, comprising displaying the predicted final mass of material in a car in consideration of immediate slewing of the slewing conveyor.
42. A method as claimed in any one of claims 34 to 41, comprising predicting the final mass of material in a car in consideration of immediate stop of the slewing conveyor.

io
43. A method as claimed in claim 42, comprising determining an estimate of the length of slewing conveyor that will continue to advance after immediate stop of the slewing conveyor, using the length estimate to determine the amount of residual material that will be added to the chute before the slewing conveyor stops, and adding the determined amount of residual material to the car mass estimate to produce a

15 predicted conveyor stop car mass estimate.
44. A method as claimed in claim 42 or claim 43, comprising displaying the predicted final mass of material in a car in consideration of immediate stop of the slewing conveyor.
45. A method as claimed in any one of claims 34 to 44, comprising displaying a car mass estimate graphically.
46. A method as claimed in claim 45, comprising displaying a car mass estimate as 25 a rectangle of increasing height as the car mass estimate increases.
47. A method as claimed in claim 46, comprising displaying a setpoint marker indicative of a target car mass adjacent the graphical car mass estimate.

30
48. A method as claimed in claim 46 or claim 47, comprising colour coding the graphical car mass estimate such that the height of the rectangle relative to the setpoint marker is represented by colour.
49. A method as claimed in claim 48, wherein the colour code is arranged such that

35 the rectangle is shown in a first colour if the current car mass is more than a defined tolerance above a car mass target, the rectangle is shown in a second colour if the current car mass is within a defined tolerance above and below the car mass target, and the rectangle is shown in a third colour if the current car mass is less than a defined tolerance below the car mass target.
50. A method as claimed in any one of claims 34 to 49, comprising displaying a slew timer indicative of the amount of time available until the slewing conveyor should commence slewing in order for a predicted final mass of material in a car to be substantially equal to a target car mass.
51. A method as claimed in claim 50, wherein the slew timer includes a graphical representation of the amount of time available until the slewing conveyor should commence slewing.
52. A method as claimed in claim 50 or claim 51, wherein the slew timer includes a numerical representation of the amount of time available until the slewing conveyor should commence slewing.
53. A method as claimed in any one of claim 50 to 52, wherein the slew timer includes a conveyor stop indicator indicative of the time that the conveyor should be stopped in order for the predicted final mass of material in a car to be substantially equal to a target car mass.
54. A method as claimed in any one of claims 51 to 53, comprising displaying the slew timer when the car mass estimate is within a defined weight of the target car mass.
55. A method as claimed in claim 54, comprising displaying the slew timer when the car mass estimate is within 15 tonnes of the target car mass.
56. A method as claimed in any one of claims 34 to 55, comprising fixing the speed of the slewing conveyor when the estimated car mass value reaches a defined estimated value.
57. A method as claimed in any one of claims 34 to 56, comprising monitoring the predicted conveyor stop car mass estimate as the car is loaded with material and automatically stopping the slewing conveyor when the predicted conveyor stop car mass estimate reaches a defined overload car mass.
58. A method as claimed in any one of claims 34 to 57, comprising using at least one train position sensor to determine the location of a train relative to the method and thereby the locations of cars of the train relative to the chute.
59. A method as claimed in any one of claims 34 to 58, comprising measuring the mass of a loaded car, and displaying measured car mass values on the display.
60. A method as claimed in claim 59, comprising storing car tare mass values, each tare mass value indicative of the tare weight of a particular car, and determining the actual weight of material loaded into the cars using the measured car mass values and the respective car tare mass values.
61. A method as claimed in claim 59 or claim 60, comprising using the measured car mass values and the corresponding predicted car mass values to produce an error correction value, the error correction value used by the mass estimator to improve the accuracy of the car mass estimate produced by the mass estimator.
62. A method as claimed in any one of claims 59 to 61, comprising calculating a variability value indicative of the variability of the measured car mass values.
63. A method as claimed in claim 62, wherein the variability value is a standard deviation value.
64. A method as claimed in claim 62 or claim 63, comprising using a desired probability value indicative of the probability of occurrence of a car overload and the variability value to calculate a target set point mass indicative of a target car mass.
65. A method as claimed in claim 64, comprising displaying the target set point mass on the display.