Field of the Invention The present invention relates to dryer for drying a mineral sample.

Throughout this specification the term "mineral sample" is used for samples of any type of geological material also including mined materials, such as ores, and fragments thereof .

Background of the Invention Samples of a mineral material, such as iron ore or another material, often need to be analysed in order to determine properties of the samples, such as an ore grade and other chemical and structural properties. The samples of the mineral material may be provided in a relatively small quantity and should have material properties that are representative of larger quantities of the mineral

material. As the moisture content has also an influence on analyses results, the samples are usually dried before being analysed.

Often large numbers of samples need to be analysed and the time required for drying of the samples has a significant influence on sample throughput. For example, a typical Australian iron ore sample may have a moisture content of approximately 10% and a required drying time using a conventional dryer at a temperature of approximately 105 ^° C (which usually is sufficiently low to avoid mineralogical damage) may be as long as 11 hours. There is need for an improved dryer that allows a reduction of the drying time.

Summary of the Invention

The present invention provides in a first aspect a dryer for drying a mineral sample, the dryer comprising:

a loading region for receiving the mineral sample, the loading region comprising a heater for heating the mineral sample from a position below the mineral sample; a component for vibrating a portion of the dryer in a manner such that the mineral sample is agitated; and

a source of radiation, the radiation being suitable for heating the mineral sample and the source being arranged to direct the radiation to the mineral sample from a position above the mineral sample;

wherein the dryer is arranged for simultaneous heating of the mineral sample from a position below the mineral sample and from a position above the mineral sample during vibrating.

The source of radiation may be a source of any radiation that is suitable for heating the mineral sample, such a microwave radiation, and in one specific example is a source of thermal infrared radiation.

The exposure of the mineral sample to heat form a position below the mineral sample and radiation from a position above the mineral sample during vibrating (and

consequently during agitating) using the dryer in

accordance with an embodiment of the present invention results in a reduction of drying time. The heater of the loading region may be provided in any suitable form, and may be a resistive, induction or oil- based heater.

The dryer may further comprise a control circuitry that is arranged to control at least a component of the dryer. The control circuitry may be arranged to control the heater of the loading region and/or the source of radiation and/or the component for vibrating the portion of the dryer. The control circuitry typically is arranged to control the heater of the loading region and/or the source of

radiation in a manner such that significant structural changes in the mineral sample are avoided. Further, the control circuitry may be arranged to control the dryer such that drying is interrupted when a moisture content of the mineral sample is below a threshold value.

The dryer may comprise a temperature sensor that is arranged to measure a temperature at a surface of the mineral sample typically without direct contact with that surface. For example, the temperature sensor may be an infrared temperature sensor or a camera that is arranged to determine the temperature of the surface of the mineral sample as a function of infrared radiation emitted from that surface. In this embodiment, the infrared sensor, the source of radiation and the control circuitry may form a feedback loop. The apparatus may also comprise a further temperature sensor that may be an electrical sensor, such as a

thermocouple, and that in use may be in contact with the mineral sample. The further temperature sensor, the heater of the loading region and the control circuitry may form a further feedback loop. The dryer may further comprise a component for determining a weight of the mineral sample during drying. The

component for determining the weight of the mineral sample may be arranged to generate an output signal that is indicative of the weight or a weight loss of the mineral sample or a rate thereof.

The control circuitry may be arranged to receive the output signal from the component for determining the weight of the mineral sample. Further, the control

circuitry may be arranged to control components of the dryer, such as the source of radiation and/or the heater of the loading region and/or the component for vibrating the base, as a function of the received output signal and as a function of the determined weight, weight loss or rate of weight loss during or after drying, which

typically is indicative of a remaining moisture content. The control circuitry may also be arranged to stop the drying (for example by interrupting a supply of electrical power to components of the dryer) when the rate of weight loss is below a predetermined threshold value.

The component for vibrating the portion of the dryer may further be operable such that at least a portion of the mineral sample is directed outside the loading region after completion of drying. The dryer may comprise a collection portion into which the at least a portion of the mineral sample can be directed. In one embodiment the control circuitry is arranged to control the component for vibrating such that, after reduction of a moisture content to or below a threshold value, the component for vibrating the mineral sample directs the mineral sample to a

collection portion of the dryer.

The present invention provides in a second aspect a method of drying a mineral sample, the method comprising the steps of:

loading the mineral sample into a loading region of a dryer;

vibrating a portion of the dryer and thereby

agitating the mineral sample;

exposing the mineral sample to heat that is directed to the mineral sample from a position below the mineral sample during agitating;

and

exposing the mineral sample to radiation during agitating, the radiation being directed to the mineral sample and from a position above the mineral sample and being suitable to heat the mineral sample.

The radiation may be any radiation that is suitable for heating the mineral sample, such a microwave radiation, and in one specific example is a source of thermal infrared radiation.

The method typically comprises determining a rate of weight loss of the mineral sample and using the control circuitry to control the drying as a function of the rate of reduction in weight. The method may further comprise a step of vibrating the portion of the dryer in a manner such that at least a portion of the mineral sample is directed outside the loading region after a reduction of a moisture content to or below a threshold value. For example, a direction of the vibration may be modified.

The invention will be more fully understood from the following description of specific embodiments of the invention. The description is provided with reference to the accompanying drawings .

Brief Description of the Drawings Figure 1 is a schematic illustration of a dryer in

accordance with a embodiment of the present invention; and

Figure 2 is a flow chart of a method in accordance with an embodiment of the present invention.

Detailed Description of Specific Embodiments

Referring initially to Figure 1, there is shown a

schematic illustration of a dryer 10 that is arranged to dry a mineral sample, such as a mineral sample.

An example for a mineral sample is iron ore which is typically pre-processed into a granular form prior to drying. An iron ore sample typically has a moisture content up to 10 percent. By heating the sample to a suitable temperature, the moisture content will eventually be reduced to a minimum amount. For an iron ore sample, a suitable temperature ranges from 100 to 110°C, such as 105°C in order to avoid structural change of the sample. A person skilled in the art will appreciate that other suitable temperature ranges are envisaged depending on the samp1e .

In this particular embodiment, the dryer 10 comprises a loading region 12 for loading the sample. Specifically, the loading region 12 may be a space or a chamber 13 within the dryer 10 which can receive the sample or a tray with the sample which could be placed into the drying chamber. Samples can typically be loaded from the top. The dryer 10 further comprises a component 14 for

vibrating a portion of the dryer 10 in a manner such that the sample is agitated during drying. In this particular embodiment as shown in Figure 1, the component 14 for vibrating a portion of the dryer 10 is arranged to vibrate the chamber 13 to agitate the sample. The dryer 10 further comprises a heater 16 for heating the sample from a position below the sample when the sample is positioned in the chamber 13. Specifically, the heater 16 is arranged such that a base 17 of the chamber 13 can be heated during vibrating. The sample may be positioned in direct contact with the base 17. In this example, the heater 16 is an oil-based heater. However, a person skilled in the art will appreciate that other suitable heaters that may or may not be in direct contact with the sample are envisaged. For example, the heater may be an induction heater.

The dryer 10 further comprises a source of radiation 18 which in this particular example is in the form of an infrared lamp. The infrared lamp 18 is positioned such that the sample can be exposed with infrared radiation from a position above the sample during vibrating.

The dryer 10 further comprises a sensor for measuring a temperature of the sample, for example, on a surface of the sample. The sensor may be a contact sensor or a non- contact sensor, such as a suitable camera. In this particular embodiment as shown in Figure 1, the dryer 10 comprises a non-contact sensor 20 in the form of an infrared sensor which determines the temperature of a top surface of the sample by measuring infrared radiation emitted from that top surface of the sample. By

determining the temperature of the surface of the sample, it can be ensured that the sample is not overheated. The person skilled in the art will appreciate that other temperature sensors are envisaged. The dryer 10 also comprises a further temperature sensor (not shown) in the form of a thermocouple which is placed below the base 17 of the chamber 13 and measures the temperature in the proximity of the base 17. The component for vibrating the chamber 13 is also arranged such that the sample is directed outside the chamber 13 and into a collector 22 after drying. The collector 22 may be in the form of a sample container. The component 14 for vibrating the chamber 13 is arranged such that a direction of vibration is selectable and is posited such that for one selectable vibration direction the dried mineral sample is directed into the collector 22.

The dryer 10 comprises a weighing component 23 for

determining a weight of the sample. The weighing

component 23 is positioned below the base 17 of the chamber 13 and measures the mass of the sample within the chamber 13 when the chamber 13 is not vibrated. The weighing component 23 determines the weight of the sample in the chamber 13 continuously, periodically or before and after the drying process and in one embodiment determines a rate of weight loss. The rate of weight loss is an indication of remaining moisture content. Generally, the weight as a function of time during the drying process can be described by an exponential curve that reaches

saturation after a certain time.

The dryer 10 also comprises a control circuitry (not shown) for controlling the heater 16, the source of radiation 18 and the component 14 for vibrating the sample as directed by a user or as a function of the determined weight, weight loss or rate of weight loss of the of the sample. Further, the control circuitry is arranged to control the weighing component 23. In one embodiment the control circuitry is arranged to interrupt the vibrating when the weighing component is in use. Further, the control circuitry is arranged such that below a threshold rate of weight loss (sample is dry or nearly dry) the control circuitry stops the drying process by controlling the radiation source 18 and/or the heater 16 and then effects a change in vibration direction such that the mineral sample is directed into the collector 22. The control circuitry may also provide information to a user that the drying process has been completed. For example, an audio or visual alarm signal may be generated to be communicated to the user.

Referring now to Figure 2, there is shown a flowchart illustrating a method 30 of drying a sample. In a first step 32, a mineral sample is loaded into a loading region of a dryer. When the mineral sample is positioned within the dryer, the sample is exposed to heat that is directed to the mineral sample from a position below the sample (step 34) and is exposed to radiation that is directed to the sample from a position above the mineral sample (step 36) . The radiation is suitable for heating the mineral sample, such as infrared radiation or microwave radiation. In a next step 38, a portion of the dryer is vibrated such that the sample is agitated.

As shown in the flowchart, the method 30 comprises a further step 40 of controlling the vibration such that at least a portion of the sample is directed outside the loading region and into a collection portion of the dryer.

In one specific embodiment the method also comprises using a control circuitry to control the heater and/or the source of radiation such that the drying process is automated. This also comprises determining a rate of weight loss of the mineral sample, which is indicative of a moisture content of the sample and interrupting the drying process once the rate of weight loss is below a threshold value after which the sample is directed to a collection portion. Although the invention has been described with reference to particular examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms .