SYSTEM Background to the Invention

[0001 ] Molten bath smelting or other pyrometallurgical operations which require interaction between the bath and a source of oxygen-containing gas utlilize several different arrangements for the supply of the gas. In general, these operations involve direct injection into the molten matte/metal. This maybe by bottom blowing tuyeres as in a Bessemer type furnace or side blowing tuyeres as in a Peirce-Smith type converter. Alternatively, the injection of gas may be by means of a lance to provide either top blowing or submerged injection. Examples of top blowing lance injection are the KALDO and BOP steel making plants in which pure oxygen is blown from above the bath to produce steel from molten iron. Another example of top blowing lance injection is the Mitsubishi copper process, in which lances cause jets of oxygen- containing gas such as an oxygen-enriched air, to impinge on and penetrate the top surface of the bath, respectively to produce and to convert copper matte. In the case of submerged lance injection, the lower end of the lance is submerged so that injection occurs within rather than from above the slag layer of the bath, to provide top submerged lancing (TSL) injection.

[0002] With both top blowing and TSL injection, the lance is subjected to intense prevailing bath temperatures. The top blowing in the Mitsubishi copper process uses a number of relatively small steel lances which have an inner pipe of about 50 mm diameter and an outer pipe of about 100 mm diameter. The inner pipe terminates at about the level of the furnace roof, well above the reaction zone. The outer pipe, which is rotatable to prevent it sticking to a water-cooled collar at the furnace roof, extends down into the gas space of the furnace to position its lower end about 500- 800 mm above the upper surface of the molten bath. Particulate feed entrained in air is blown through the inner pipe, while oxygen enriched air is blown through the annulus between the pipes. Despite the spacing of the lower end of the outer pipe above the bath surface, and any cooling of the lance by the gases passing through it, the outer pipe burns back by about 400 mm per day. The outer pipe therefore is slowly lowered and, when required, new sections are attached to the top of the outer, consumable pipe.

[0003] The lances employed for TSL injection are much larger than those for top blowing, such as in the Mitsubishi process described above. A TSL lance usually has at least an inner and an outer pipe, as assumed in the following, but may have at least one other pipe concentric with the inner and outer pipes. Typical large scale TSL lances have an outer pipe diameter of 200 to 500 mm, or larger. Also, the lance is much longer and extends down through the roof of a TSL reactor, which may be about 10 to 15 m tall, so that the lower end of the outer pipe is immersed to a depth of about 300 mm or more in a molten slag phase of the bath, but is protected by a coating of solidified slag formed and maintained on the outer surface of the outer pipe by the cooling action of the injected gas flow within. The inner pipe may terminate at about the same level as the outer pipe, or at a higher level of up to about 1000 mm above the lower end of the outer pipe. Thus, it can be the case that the lower end of only the outer pipe is submerged.

[0004] The inner pipe of a TSL lance may be used to supply feed materials, such as concentrate, fluxes and reductant to be injected into a slag layer of the bath, or it may be used for fuel. An oxygen containing gas, such as air or oxygen enriched air, is supplied through the annulus between the pipes. When submerged injection within the slag layer of the bath commences, oxygen-containing gas and fuel, such as fuel oil, fine coal or hydrocarbon gas, are supplied to the lance and a resultant oxygen/fuel mixture is fired to generate a flame jet which impinges into the slag. This causes the slag to slop within the bath resulting in significant bath movement. This bath movement, together with injection of gases or other materials via the lance results in movement of the lance due to induced forces. The range of motion to which a top submerged lance is subjected has the potential to provide important information regarding process operations occurring in the molten bath.

[0005] According to conventional practice, the lance is controlled by an operator who decides at what level the lance tip should be positioned and controls this by way of raising or lowering the lance relative to the bath by means of a lifting apparatus attached to the lance. Such an arrangement may include a support or guide for the lance, called a lance trolley, the lance trolley being connected by a cable to a hoist whereby a motor control system allows positioning of the lance tip relative to the molten bath within the vessel. A lance height indicator, which may be controlled from a slide wire transmitter driven from the lance drum, is employed to provide an indication of the position of the lower end of the lance within the reactor. Operators are instructed to make manual observations regarding lance movement and in time, learn to intuitively recognise which range of motion of the lance is indicative of optimal or sub-optimal conditions in the molten bath. For example, an operator can position the lance in the molten bath by monitoring the movement of the lance by eye. The extent of movement of the lance can be used by an operator with some experience, to approximate the depth to which the tip of the lance is submerged in the molten bath.

[0006] The discussion of the background to the invention included herein including reference to documents, acts, materials, devices, articles and the like is intended to explain the context of the present invention. This is not to be taken as an admission or a suggestion that any of the material referred to was published, known or part of the common general knowledge in the patent area as at the priority date of the claims.

[0007] It would be desirable to provide one or more sensors for monitoring an operating condition in a molten slag bath.

Summary of the Invention

[0008] According to an aspect of the present invention there is provided a sensing device for determining an operating condition in a molten bath of a top-submerged lancing injector reactor system, at least a lower end of a lance being positioned in the molten bath in a submerged position, the sensing device being mounted on the lance and being configured to sense one or more movements of or forces applied to the lance, wherein the sensed movements or forces are indicative of the operating condition in the molten bath.

[0009] Examples of suitable sensing devices include orientation sensors generally, and more specifically one or more of an accelerometer, a gyroscope and/or a magnetometer. An accelerometer for instance, can be used to sense the orientation of the lance by detecting the magnitude and direction of movements of the lance, acceleration of the lance in various directions and/or the g-forces to which the lance is subject. Such orientation sensors may be used alone or in combination to provide the requisite functionality to the sensing device.

[00010] Since bath slopping is regarded typical to normal operating conditions within the reactor, and bath slopping ordinarily causes involuntary movement of the lance, an assessment of the operating conditions in the molten bath can be based on lance movement patterns. For example, lance movement is impacted by variable conditions including lance position within the reactor including lance proximity to the molten bath; slag levels, variations in slag viscosity, molten bath temperature and the like. Where a lance movement pattern indicates an undesirable operating condition, such that the lance is submerged too deep in the molten bath, or not submerged at all, or that the slag is too viscous, this determination may be used to make adjustments to the operating conditions within the reactor system with the ultimate aim of improving the efficiency of the operation.

[0001 1 ] In an embodiment, the sensing device is mounted distal to the lower end of the lance. This configuration protects the sensing device from the conditions in the molten bath by positioning the sensing device as far away from the molten bath as practical, i.e. by mounting the sensing device towards the end of the lance that might be mounted on a lifting apparatus such as a lance trolley and hoist, rather than the lower end of the lance which will be submerged in the molten bath during operation. [00012] The sensing device may be wirelessly coupled or hard wired to a receiver to which a plurality of sensed signals are transmitted. The receiver may include processing means configured to analyse the sensed signals to determine at least the magnitude and direction of lance movement. Alternatively, part or all of the processing functionality may be included in a remotely located base station. [00013] The processing means may generate output to visually indicate to an operator of the top-submerged lancing injector reactor system, the operating conditions in the molten bath as a function of the sensed signals. In one embodiment, the output is in the form of one or more graphical plots that provide a visual indicator of any displacement of the lance in at least two dimensions. Preferably, displacement of the lance is indicated in three dimensions, i.e. in the X, Y and Z planes. The graphical plot may take the form of a movement map or could take the form of a bar chart or similar. In other embodiments, the visual indicator takes the form of a numerical or colour display which an operator recognises as indicating desirable, undesirable or neutral conditions in the bath, for example.

[00014] According to another aspect of the present invention, there is provided a top-submerged lancing injector reactor system including: a molten bath; a lance being moveable between a submerged position and an unsubmerged position, the lance having a lower end and an upper end, the lower end configured to be lowered into the molten bath in the submerged position; and a sensing device mounted on the lance and being configured to sense one or more movements of or forces applied to the lance, wherein the sensed movements or forces are indicative of an operating condition in the molten bath.

[00015] In an embodiment, the lance is mounted on a lifting apparatus operable to position the lance between the submerged position and the unsubmerged position. The lance is preferably mounted on the lifting apparatus at a point that is intermediate to the lower end of the lance and an upper end of the lance. Moreover, the sensing device is preferably mounted proximal to the upper end of the lance to protect the sensing device from exposure to the conditions in the molten bath.

[00016] Suitable sensing devices include orientation sensors generally, and more specifically one or more of an accelerometer, a gyroscope and/or a magnetometer. In one particular embodiment, the sensory device is an inertial measurement unit (IMU).

[00017] The top-submerged lancing injector reactor system may further include a receiver configured to receive a plurality of sensed signals transmitted by the sensing device. The receiver may include processing means configured to analyse the sensed signals or alternatively, this functionality may be included in a remote device such as a base station.

[00018] The processing means may generate output to visually indicate the operating conditions of the molten bath as a function of the sensed signals. In one particular embodiment, the output generated by the processing means may comprise one or more graphical plots to provide a visual indicator of displacement of the lance in at least two dimensions. Preferably, displacement of the lance is plotted with respect to three dimensions. [00019] According to yet another aspect of the present invention, there is provided a method for determining an operating condition in a molten bath of a top-submerged lancing injector reactor system, the method including the following steps: providing a sensing device mounted on a lance; lowering at least a lower end of a lance into the molten bath towards a submerged position; generating one or more sensed signals in response to movements of and/or forces applied to the lance; and transmitting the sensed signals to a receiver; processing the sensed signals to determine at least the magnitude and direction of lance movement or a force applied thereto; wherein movement of or the force applied to the lance is indicative of an operating condition in the molten bath.

[00020] In one form of the method, the receiver includes processing means which derives data regarding the operating condition of the molten bath as a function of the sensed signals.

[00021 ] In another form of the method, the receiver is communicatively coupled to a base station having processing means which derives data regarding the operating conditions of the molten bath as a function of the sensed signals.

[00022] The step of sensing one or more movements of the lance preferably includes determining a displacement of the lance in the X, Y and Z axes.

[00023] The step of sensing one or more movements of or forces applied to the lance may include one or more of measuring an acceleration of the lance; measuring a rotational movement of the lance; and/or measuring vibration and/or strain.

Brief Description of the Drawings

[00024] The present invention will now be described in greater detail with reference to the accompanying drawings. It is to be understood that the embodiments shown are examples only and are not to be taken as limiting the scope of the invention as define din the claims appended hereto.

[00025] Figure 1 is a partially cut away schematic of a molten bath smelting furnace including a top submerged lance in accordance with the prior art.

[00026] Figure 2 is a schematic showing a top submerged lance in accordance with the prior art. [00027] Figure 3 a schematic illustration showing a top submerged injecting lance fitted with the sensing device of the present invention.

[00028] Figure 4A is a schematic showing a lance positioned out of the molten bath. [00029] Figure 4B is a corresponding graphical plot indicating displacement of the lance in the X, Y and Z axes when the lance is positioned out of the molten bath in accordance with the schematic shown in Figure 4A.

[00030] Figure 5A is a schematic showing a lance positioned just above the surface of a molten bath. [00031 ] Figure 5B is a corresponding graphical plot indicating displacement of the lance in the X, Y and Z axes when the lance is positioned just above the surface of the molten bath in accordance with the schematic shown in Figure 5A.

[00032] Figure 6A is a schematic showing a normal operating position of a lance relation to the molten bath. [00033] Figure 6B is a corresponding graphical plot indicating displacement of the lance in the X, Y and Z axes when the lance is in a normal operating position in the molten bath in accordance with the schematic shown in Figure 6A.

[00034] Figure 7A is a schematic showing a lance exposed to an abnormal operating condition in the molten bath. [00035] Figure 7B is a corresponding graphical plot indicating displacement of the lance in the X, Y and Z axes when the lance is exposed to an abnormal operating condition in the molten bath in accordance with the schematic shown in Figure 7A.

[00036] Figure 8 is a flowchart showing a method for determining an operating condition in a molten bath of a top-submerged lancing injector reactor system in accordance with an embodiment of the present invention.

Detailed Description

[00037] Referring firstly to Figure 1 , there is shown an exemplary top-submerged lancing injector reactor system 100. The reactor 102 has a cylindrical shell 104 closed at its top end by an inclined roof 106 from which an off-take flue 108 projects upwardly to an off-gas boiler/heat exchanger 1 10. In Figure 1 , a section of the shell 104 has been removed to enable the interior of the reactor 102 to be viewed, although the shell 104 is circumferentially continuous at all levels in its height, apart from tap holes. The roof 106 has an inlet 1 12 down through which a top submerged injecting lance 1 14 extends so that a lower end portion of the lance 1 15 is submerged in the molten bath 1 16. The reactor 102 also has a feed port 1 18 opening through roof 106 to enable raw materials for a required pyro-metallurgical operation to be charged into bath 1 16, and a burner port 120 for enabling insertion of a burner 122 if required for heating the reactor. Lance 1 14 has connectors 124 that enable connection of lance 1 14 to separate sources of fuel/reductant and oxygen-containing gas, to enable the separate passage of these materials down through lance 1 14 and to mix at the lower, outlet end of lance to feed a combusting mixture. The combustion of the fuel and oxygen mixture generates a combustion zone in the molten bath 1 16 at the lower, outlet end of lance 1 15, as well as strong turbulence in the molten bath 1 16 that causes the raw materials charged through port 1 18 to be dispersed in the molten bath to give rise to the required pyro-metallurgical reactions therein.

[00038] The lance 1 14, as depicted in Figure 2, is a schematic illustration of the lower end of one exemplary form of top submerged injecting lance 1 14 to be fitted with the sensing device of the present invention. The lance 1 14 comprises an outer pipe 202, an inner pipe 204 and, between pipes 202 and 204, an intermediate pipe 206. The pipes 202, 204 and 206 are substantially circular in cross-section and substantially concentrically arranged. An annular passage 208 defined between pipes 202 and 206 enables the supply of air, while a passage 210 defined between pipes 204 and 206 enables the supply of oxygen. The bore 212 defined by pipe 204 enables the supply of fuel/reductant. As shown, pipes 204 and 206 terminate a short distance, relative to the overall length of lance 1 14, above the lower end of pipe 202 to provide a mixing chamber 214 in which the fuel/reductant, air and oxygen mix to facilitate efficient combustion of the fuel at the lower end of pipe 202. The lance 1 14 may have a length of up to about 25 meters and an outside diameter of up to about 0.5 meters for commercial operation. A pilot plant version of lance 1 14 may be only about 4 meters long and about 0.075 meters external diameter. [00039] Referring now to Figure 3, an exemplary form of the sensing device for determining the operating conditions in a molten bath is shown in combination with the lance of Figure 2. The sensing device 302, is shown enlarged relative to the diameter of lance 1 14. The sensing device 302 is mounted on the lance 1 14 and senses movement of the lance and/or forces applied to the lance, such as an acceleration of g-force, in three dimensions, substantially in the horizontal plane (X axis 312 and Y axis 314), and substantially in the vertical plane (Z axis 316). Preferably, the sensing occurs continuously throughout operation of the lancing injector reactor system 100 (see Figure 1 ), although it is envisaged that sensing could be programmed to occur at predetermined intervals to provide a check or point of comparison for future sensed signals. The movements sensed by the sensing device 302 are indicative of the operating condition in the molten bath 1 16 (see Figure 1 ) as will be detailed in the following paragraphs.

[00040] Since the contents of a top-submerged lancing injector are not visible, it can be very difficult for an operator to have any real appreciation of the operating conditions in the molten bath. Typically, an operator will learn by experience how the lance will respond to and behave in particular conditions. The injection of oxygen- containing gas and fuel into the molten bath causes the slag to slop in the bath. The slopping or bath movement, together with forces induced by gases or other materials injected via the lance itself, cause various involuntary movements of the lance. The magnitude and direction of movement, together with the force and/or acceleration (referenced as "G" on each directional axes in Figure 3) of a lance that is at least partially submerged in the molten bath is therefore a reliable indicator of the operating conditions in the molten bath. [00041 ] For example, as illustrated in Figure 3, the sensing device 302 is mounted distal to the lower end 304 of the lance 1 14. This configuration distances the sensing device 302 from exposure to the conditions in the molten bath 1 16 (see Figure 1 ). Any movement occurring at the lance tip 310, i.e. the extremity of the lower end of the lance 304, is substantially translated to the upper end of the lance 306. Accordingly, the sensing device 302 can be mounted distal to the lower end 304 of the lance 1 14 to be submerged in the molten bath, and still provide a useful indication as to the operating conditions in the molten bath. [00042] The lance 1 14 is mounted on, or fixed to a lifting apparatus (not shown) at a point 308 on the lance which is intermediate to the lower end 304 and the upper end 306 of the lance. Since the positon of the lance 1 14 is only fixed at this intermediate point 308, any movement induced by forces acting on the lance tip 310 will be translated through the entire length of the lance. Whilst mounting the lance 1 14 on a lifting apparatus in itself provides a source of physical restraint which could be additionally provided by means of an separate physical constraint elsewhere connected to the lance 1 14, translation of a movement or force applied to the lance tip 310 will occur in any event due to the significant forces to which a top-submerged lance 1 14 is subject during operation.

[00043] The range of movements and/or forces that can be measured by the sensing device 302 include at least: displacement in up to three dimensions, i.e. the X, Y and Z planes; acceleration forces; rotational movement; and vibration or strain. Measuring displacement of the lance in at least two dimensions, e.g. X and Y plane displacement is reliable indicator of displacement due to bath slopping. Measuring displacement in a third dimension, e.g. Z plane movement caused by injection under a normal fluid slag is a further indicator of operating conditions.

[00044] The proposed range of lance movements can be sensed by sensing device which include one or more of a variety of independent sensors such as an orientation sensor, an accelerometer, a gyroscope or a magnetometer. Alternatively the functionality of a variety of sensors can be provided in a single sensing device in the form of an Inertial Measurement Unit (IMU).

[00045] The sensing device is coupled to a receiver configured to receive a plurality of sensed signals transmitted from the sensing device. If the receiver includes processing means, the sensed signals are analysed by the receiver to determine at least the magnitude and direction of lance movement. Alternatively, if the receiver does not include processing means, this functionality may be included at a remotely located base station. In any case, the processing means analyses the sensed signals and generates output to visually indicate the operating conditions of the molten bath. The output is in a form which can be readily interpreted by a top-submerged lancing injection reactor operator. For example, the output can be provided in the form of one or more graphical plots which provide a visual indicator of the displacement of the lance in at least two dimensions. Examples of such graphical plots are described below with reference to Figures 4B, 5B, 6B and 7B.

[00046] Other functionality such as data acquisition, storage and signal processing may also be built into the receiver. Alternatively, part or all of these functionalities may be included in a remote device such as a base station.

[00047] The receiver may be wirelessly coupled to the base station via a wireless network such as Bluetooth, WiFi, Zig-Bee or wireless LAN, or wireless WAN such as 3G or 4G networks or other wireless networks which may be available from time to time. Alternatively, the receiver may be hard wired to the receiver or remote base station. Ideally, the data transmitted to the receiver is processed in real-time, although it is contemplated that data could be obtained from the receiver in batches and subsequently processed off-line. Real-time processing of sensed data supports real-time monitoring and adaptation of operating procedures to suit the present operating conditions. [00048] Referring now to Figures 4A and 4B there is shown a first example of an operating condition that can be sensed using the sensing device of the present invention. Referring firstly to Figure 4A, the lance is "out of bath", that is, the lance tip 310 is not submerged in the molten bath 1 16 and accordingly will have no forces exerted there upon by slopping or bath movement. In this condition, as would be expected, the corresponding output or graphical plot 400 shown in Figure 4B shows no displacement of the lance in the X, Y or Z axes. An "out of bath" condition is clearly undesirable, not only because gases or other materials injected via the lance 1 14 are not injected directly into the molten bath 1 16, but also because this can cause additional wear on the lance tip 310 which will not be protected by a coating of solidified slag which forms on the lance tip during normal operating conditions.

[00049] Referring now to Figure 5A there is schematically shown a "top jetting" condition, where the lance 1 14 position is just short of being submerged in the molten bath 1 16. The lance tip 310 is positioned just above the molten bath 1 16 surface. This condition is undesirable for similar reasons to the "out of bath" condition, i.e. gases or other materials are not injected directly into the molten bath 1 16 and the lance tip 310 is caused to be prematurely worn. A "top jetting" condition is indicated by a graphical plot 500 as shown for example in Figure 5B. This graphical plot 500 shows relatively homogenous movement of the lance in the X, Y and Z planes with similar ranges of movement of similar magnitude in three dimensions. This pattern of movement results from limited impact of slopping or bath movement on the lance. [00050] Referring now to Figure 6A there is shown a normal or desirable operating condition wherein the lance 1 14 is submerged in the molten bath 1 16 at the optimal depth and the slag in the molten bath is fluid. In such desirable operating conditions the pattern of movement of the lance 1 14 will typically show some irregularities with respect to displacement of the lance in the X, Y and Z planes as evidenced by the graphical plot 600 shown in Figure 6B. This irregular pattern of lance displacements of similar magnitudes is caused by regular bath slopping facilitated by a fluid slag with the lance tip submerged at an optimal depth.

[00051 ] Referring now to Figure 7A and 7B, there is shown an example of an abnormal operating condition, wherein the lance 1 14 is submerged too deep in the molten bath 1 16. The resulting graphical plot 700 shown in Figure 7B indicates erratic displacement of the lance in the X, Y and Z planes. Moreover, the magnitude of the displacements is random in nature. Other factors that can result in similar graphical plots include where the slag is too viscous resulting in unpredictable bath slopping which may additionally be indicative of a bath temperature that is too low. [00052] Normal acceleration forces can also be measured which will arise from interactions with the molten bath due to phenomenon such as induced wave motion or bath slopping.

[00053] Through calibration of the sensing device normal operating conditions can be regularly or continuously compared to calibrated conditions such that the operator can adjust the operational parameters of the reactor responsive to sensed anomalies. For instance, the device may be configured to generate a visible, audible or tactile alert if undesirable operating conditions are detected. A visible alert may take the form of a graphical plot as described with reference to the Figures. For instance the rings on the graphical plots could be colour coded to more clearly indicate to an operator that when the lance movement in a direction enters a "red zone" for example, that this indicates an undesirable condition within the bath and that restorative action should be taken. Conversely, if the plot stays within a "green zone" for example, this might indicate that conditions within the bath are desirable, whilst a "yellow zone" might indicate that conditions should be closely monitored. Alternatively, the visible alert may be simplified into a numeric or colour coded display, for example a single green, yellow or red light to indicate desirable, neutral or undesirable conditions within the bath. Whichever form the alert takes, it is intended to alert the operator to undesirable conditions in the reactor in real-time allowing corrective action to be taken in a timely manner.

[00054] Referring now to Figure 8, there is shown a flowchart illustrating the method 800 for determining an operating condition in a molten bath of a top- submerged lancing injector reactor system as hereinbefore described. The method includes at step 810 providing a sensing device mounted on a lance. At least a lower end of the lance is positioned or lowered into the molten bath towards a submerged position at step 820. Sensed signals are generated in response to movement of the lance at step 830 and transmitted to a receiver at step 840. At step 850 the sensed signals are processed to determine at least the magnitude and direction of lance movement. The magnitude and direction of lance movement is indicative of one or more operating conditions in the molten bath at step 860. The method is iterative such that the sensed signals are either generated continuously, or at regular, or even random intervals to provide ongoing monitoring of the operating conditions in the molten bath.

[00055] The sensing device of the present invention confers various advantages and benefits to the operation of top-submerged lancing injector reactors. The operation of the lance itself acts as a sensor to indicate the conditions in the molten bath by means of the sensing device. By measuring lance motion various reactor operating characteristics are obtained and can be measured, recorded and compared with desirable or optimal plant operating conditions to enable corrective action to be taken in a timely manner responsive to sensed conditions which are sub optimal. Therefore the efficiency of the reactor can be optimised. [00056] Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereto.

[00057] While the invention has been described in conjunction with a limited number of embodiments, it will be appreciated by those skilled in the art that many alternative, modifications and variations in light of the foregoing description are possible. Accordingly, the present invention is intended to embrace all such alternative, modifications and variations as may fall within the spirit and scope of the invention as disclosed.