AU707321B2

AU707321B2 - Controller and process for explosives mixing and loading

Info

Publication number: AU707321B2
Application number: AU47978/96A
Authority: AU
Inventors: Andrew David Hunter
Original assignee: Orica Australia Pty Ltd
Current assignee: Orica Explosives Technology Pty Ltd
Priority date: 1995-03-10
Filing date: 1996-03-07
Publication date: 1999-07-08
Anticipated expiration: 2016-03-07
Also published as: AU4797896A

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "CONTROLLER AND PROCESS FOR EXPLOSIVES MIXING AND LOADING" The following statement is a full description of this invention, including the best method of performing it known to me:- P:\OPER\PHH47978 96 RES 26/4/99 -2- CONTROLLER AND PROCESS FOR EXPLOSIVES MIXING AND LOADING This invention relates to a controller and process for use in the manufacture of explosives compositions and/or delivery of said explosives compositions to a desired location such as a blasthole. In particular, the present invention relates to a modular controller which may be used interchangeably on a variety of explosive manufacturing and/or delivery equipment.

Civilian mining, quarrying and excavation industries commonly use bulk or packaged explosive formulations as a principal method for breaking rocks and ore for mining, building tunnels, excavating and similar activities.

Explosive compositions comprising particular oxidiser salts and a fuel have S been known for many years as relatively inexpensive and reliable explosives and the S most commonly used of these is ANFO, a mixture of ammonium nitrate (AN) and about 6% w/w fuel oil. ANFO is frequently used in dry conditions but less commonly in wet S 15 conditions because the AN particulars absorb water, making the ANFO difficult to detonate and adversely affecting blast performance.

Emulsion explosives are preferred in areas where wet conditions are common because of their superior water resistance compared to ANFO. However they are significantly more expensive. Water-in-oil emulsion explosive compositions were first disclosed by Bluhm in United States Patent 3,447,978 and comprise a discontinuous aqueous phase comprising discrete droplets of an aqueous solution of inorganic oxygen-releasing salts (oxidiser salt solution); a continuous waterimmiscible organic phase (continuous organic phase) throughout which the droplets of oxidiser salt solution are dispersed and an emulsifier which stabilises the droplets of oxidiser salt solution throughout the continuous organic phase in the form S• of an emulsion. Such emulsions which comprise very little water or adventitious water only in the discontinuous phase are often more correctly referred to as melt-in-fuel emulsion explosives.

Generally the emulsions themselves are not readily detonable and in order to o form an explosive they are generally mixed with sensitising agents such as a self o explosive (eg. trinitrotoluene or nitroglycerine) or a discontinuous phase of void p:\oPER\PHH\47978-96.RES -2614/99 -3agents. Suitable void agents include glass microballoons, plastic microballoons, expanded polystyrene beads and gas bubbles including bubbles of entrained air.

In order to take advantage of the low cost of ANFO and the superior water resistance of emulsions, ANFO and emulsions are often blended together to provide explosives which are commonly referred to as "heavy ANFO's". Compositions comprising blends of emulsion and AN or ANFO are described, for example in Australian Patent Application No. 29408/71 (Butterworth) and US Patents 3,161,551 (Egly et al) and 4,357,184 (Binet et al).

When explosives are used in the mining industry, rock is fractured by drilling blastholes then filling them with bulk or packaged explosive compositions which are subsequently detonated. Bulk explosives are generally less expensive per unit mass than packaged explosives hence bulk explosives are preferred, particularly at large mine sites where many hundreds of tonnes of explosives may be needed for a single blast. Packaged explosives also suffer the drawback that they must be manually o• 15 loaded into blastholes whereas bulk explosives may be readily loaded by mechanised means. Bulk explosives may be manufactured either at a manufacturing facility and S•transported in a specially designed truck to the mine or preferably mixed on-site in manufacturing units located on trucks (called mobile manufacturing units or MMU's).

The transport trucks and MMU's are provided with the mechanised means for loading 20 bulk explosive into blastholes; the loading is usually carried out by auguring, pouring, 0° pumping or blow loading, the method used depending on the type of product. Loading by pumping is usually carried out by using a mechanical or pneumatic pump to push explosives compositions through a delivery hose into the blastholes. Blow loading of an explosive composition typically involves the use of compressed gas to blow the explosive through a delivery hose into blastholes and is a commonly used delivery method for ANFO.

Both MMU's and fixed manufacturing facilities store relatively large quantities of chemical components which are eventually mixed together to form explosives compositions. For example, MMU's comprise several large storage containers for 0 storing fuel oil, emulsion, particulate oxidiser salts, water and other explosives components. These components can be mixed in differing proportions to provide P:\oPER\PIIH\41978-96.RES 26/4/99 -4- ANFO, or various formulations of emulsion and heavy ANFO.

MMU's and fixed manufacturing facilities are expensive to construct and maintain and are generally adapted for economy of scale. The larger facilities are designed to deliver hundreds of tonnes of explosive composition in a single manufacturing run at a production rate of between 70 and 200 kg per minute. These manufacturing facilities are designed to fulfil the needs of high volume markets such as large mine sites.

The low volume markets such as small quarries which may need only a few tonnes of explosives per blast are often supplied with explosives by small scale, transportable manufacturing units such as those known as ASIAMASTER manufacturing units (ASIAMASTER is a trade mark of Orica Australia Proprietary Limited.) Such units are small enough to be moved by being placed on a truck or trailer or they may be adapted to be towed.

Predictable and optimal explosive performance requires an exact, even S 15 blending of components in specified proportions. Explosive manufacturers need to be S, able to reliably manufacture explosive formulations to the specification and quality S•required. In order to operate with maximum efficiency and economy precise control over the volume of explosives manufactured and, where necessary, the amount metered into each blasthole is desired.

All explosives manufacturing units have control settings, meters and the like which are used by operators to monitor and adjust the flow rates of components and I the rate at which the components are mixed. Small transportable manufacturing units have built in meters, valves and the like for control of manufacture by an operator standing beside the unit. On MMU's these functions are generally controlled by the S 25 driver/operator from the vehicle cabin using systems which are purpose built and integral with the truck.

Such systems work by monitoring parameters of the manufacturing process, for example auger speed may be monitored by rpm counters while pumping rate may be monitored from pump speed. The operator needs to know how these parameters relate to actual quantities of components delivered into the manufacturing process.

Consequently, before commencing a manufacturing run, the operator carries out a P:\OPER\PI{Hk47978-96.RES 26/4J99 calibration of a particular active transport means (such as pumps, augers and the like) by seeing how much material each delivers at a given speed. The operator uses these calibration values to calculate at what speed each active transport means should be allowed to run to provide a certain blend of materials. Appropriate times are set and the process is commenced; each active transport means continuing to work until the timer signals that they stop.

One of the problems of this type of system is that it requires that the rate of each active transport means is constant, which may not be desirable. Furthermore, the prior art relies on a separate control system being built into every manufacturing facility. We have now found that a portable, self-contained modular control unit, which is not vehicle specific can be used to provide more accurate control of explosives S" manufacturing processes.

The current invention therefore provides a modular controller a modular S: controller when used in explosives' manufacturing and/or delivery equipment, which 15 modular controller comprises: a memory means for receiving and storing process information and calibration values; a data processor means for performing calculations using said process information and calibration values and for comparing some of said process information .SO and calculation results with target values; and a display unit which can display information and calculating results from said memory means and data processor; wherein said data processor is adapted to supply a control signal to an appropriate part of said equipment in response to a target value being reached.

The current invention further provides a method a method of manufacturing S• and/or delivering explosives, wherein a modular controller is connected to explosives; manufacturing and/or delivery equipment, the modular controller comprising: a memory means for receiving and storing process information and calibration values; a data processor means for performing calculations using said process information and calibration values and for comparing at least some of said process P:\OPER\PHH\47978-96.RES 26/4/99 5A information and calculation results with target values; and a display unit which can display information and calculation results from said memory means and data processor, and wherein said data processor supplies a control signal to an appropriate part of said equipment in response to a target value being reached.

The process information may comprise data monitored directly from the process including pump speeds, hydraulic pump pressures, material flow rates, temperatures and so forth. The target values may relate to maximum or minimum s* *s 45

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5* desired values for these process parameters and may be imputed to the memory or preprogrammed in the data processor.

In a preferred embodiment, the process parameters monitored relate to an active transport means, that is the means by which the explosives precursors are transported from storage containers to the desired point of addition to the process. For example, where the precursor is a solid, the active transport means may comprise an auger or the like and where the precursor is a liquid the active transport means may comprise a pump or the like.

Where an active transport means is to be monitored, the process operator carries out a calibration of the active transport means by measuring its delivery rate. For example, an auger may be found to have a calibration value of 5 kg per revolution of the operating motor. The calibration factor obtained may then be So input to the modular controller.

As the process information is monitored and the information fed to the 15 memory means of the control module the data processor takes the information from the memory means and using the calibration factor, converts the process parameter information into another form such as material flow rate. For example, if an auger has a calibration factor of 5 kg/revolution, monitoring the revolutions 00..

of the auger motor allows the exact mass of solid delivered by the auger to be calculated by the data processor. By measuring the actual mass of solid delivered and stopping the process after the required amount has been delivered is inherently more accurate than using the time-based system of the prior art.

The process parameter monitored may also relate to maintaining the safe running of the process. For example a maximum and minimum target pressure may be input to the controller for a given pump. If the pump pressure reaches *either of these target values the data processor may issue a control signal which stops the pump. Optionally an audible or visual alarm may also be triggered when a target value is reached. This provides a level of pump protection against "dry running" or "dead heading" which may lead to a detonation of entrapped explosive.

The measured parameter of each transport means is converted by its o calibration factor into a flow rate in kg/min. These flow rates may be summed together to give a total flow rate of ingredients being delivered at any point in time. While

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The control module of the current invention may be used to control the manufacture of any formulation of explosives, simply by changing the configuration or selecting one of a range of configurations held in memory. The control module may be removably connected to any type of explosives manufacturing facility including fixed site manufacturing plants or relocatable plants including mobile manufacturing units and units for use underground. Preferably the control module may be easily connected to a manufacturing facility by a multi-pin electrical connection plug or the like.

The display means of the controller of the current invention may be of any convenient type known in the art. in a preferred embodiment the control module of the current invention can display a range of menus and different displays. For example one menu of the controller may be able to display a list of precursors 15 against the mass of each used in the process while another menu may display the various calibration factors entered. Preferably such information may also be stored in the memory means so that a history of several manufacturing runs may be kept.

The manufacturing facility for use with the control module of the current invention may additionally have a delivery means for loading explosives compositions from the mixing device down a blasthole. The delivery means may comprise any apparatus known in the art for loading blastholes by auguring, pouring, pumping, blow loading or the like. It is particularly preferred that the control module be able to control the amount of explosive delivered into each blasthole.

The control module of the current invention is preferably enclosed in arobust, waterproof container so that it may easily be transported from place to place and resist damage in the relatively rough conditions of mine sites.

The control module of the current invention may optionally comprise means for interfacing with printers, modems, radio-link data transfer systems and GPS satellite navigation. Preferably data from the control module may be down loaded to a personal computer.

1The control module of the current invention will now be described with reference to the following non-limiting example;

EXAMPLE

A modular controller of the current invention was used to control a process for manufacture of an explosive composition comprising particulate ammonium nitrate (AN) blended with a water-in-oil emulsion.

A modular controller was constructed using a commercially available process controller to measure inputs from flow/speed sensors located in the product, AN and emulsion pumps of an explosives manufacturing facility. A single 9-core cable connected the modular controller to the manufacturing facility. The data processor displays via back lit graphical LCD display. The operator adjusted calibration values via a menu based calibration system into memory for each of the product, AN, fuel oil and emulsion pumps by using six push buttons and then pushed "GO" button to initiate the manufacturing process. An output relay in the data processor opened a main hydraulic valve, starting the process pumps to run S 15 at pre-determined speeds, set by manual hydraulic flow controls. The data monitored by the flow/speed sensors located in the product, AN, fuel oil and emulsion pumps were returned to memory and the data processor used the calibration values to convert the data to product, AN, fuel oil and emulsion flow rates. These flow rates were summed together to calculate the overall delivery rate. When the amount of explosives composition delivered reach a predetermined quantity a control signal issued by the data processor shut down the AN, fuel oil and emulsion pumps.

diagrammatic representation of the set up of the control module is depicted in Figure 1. The data processor, memory and display are components of the control module. The operator, process and communications link are external to the control module. The operator inputs directly to the data processor which may process these inputs and feed various parameters and information into memory and/or the display means. The data processor is also responsible for sending control signals to the various elements of the process. Process information is relayed back to the data processor to be processed, fed into memory or displayed for the operator. A communications link to the data processor can be used to input data, commands, information etcetera or accept same from the data processor. The communications link may comprise any suitable means for P:\OPER\PHH\47978-96.RES 26/4/99 -9transmitting and manipulating data including a personal computer.

While the invention has been explained in relation to its preferred embodiments it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

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Claims

2. A modular controller according to claim 1 wherein the process information comprises process parameters relating to active transport means.
3. A modular controller according to claim 2 wherein the active transport means is an auger or a pump.
4. A modular controller according to any one of claims 1 to 3 wherein said process information comprises one or more types of data chosen from pump speed, hydraulic pump pressure, material flow rate and temperature.
5. A modular controller according to any one of the preceding claims wherein target values can be input to the memory or preprogrammed in the data processor.
6. A modular controller according to any one of the preceding claims which further comprises audible or visible alarms which are triggered when a target value is reached. P:\OPER\PHH\47978-96.RES 2614/99
11- 7. A modular controller according to any one of the preceding claims comprising a means for interfacing with any one or more printers and/or radio-link data transfer systems and/or satellite navigation systems. 8. A modular controller according to any one of the preceding claims comprising a robust, waterproof container. 9. A modular controller when used in explosives' manufacturing and/or delivery equipment and substantially as herein described with reference to the accompanying drawings and/or example. 0* 10. Explosives' manufacturing and/or delivery equipment including a modular controller according to any one of claims 1 to 9. 15 11. A method of manufacturing and/or delivering explosives, wherein a modular ,to° controller is connected to explosives; manufacturing and/or delivery equipment, the modular controller comprising: a memory means for receiving and storing process information and calibration values; 20 a data processor means for performing calculations using said process information and calibration values and for comparing at least some of said process information and calculation results with target values; and a display unit which can display information and calculation results from said memory means and data processor, 25 and wherein said data processor supplies a control signal to an appropriate part of said equipment in response to a target value being reached.
12. A method of manufacturing explosives according to claim 11 wherein the process information comprises process parameters relating to active transport means.
013. A method of manufacturing explosives according to claim 12 wherein the active A method of manufacturing explosives according to claim 12 wherein the active P:\OPER\PHH47978-96.RES 26/4/99 12- transport means is an auger or a pump.
14. A method of manufacturing explosives according to any one of claims 11 to 13 wherein said process information comprises one or more types of data chosen from pump speed, hydraulic pump pressure, material flow rate and temperature. A method of manufacturing explosives according to any one of claims 11 to 14 wherein target values can be input to the memory or preprogrammed in the data processor of the modular controller.
16. A method of manufacturing of explosives according to any one of claims 11 to wherein the modular controller further comprises audible or visible alarms which *0 are triggered when a target value is reached. 15 17. A method of manufacturing of explosives according to any one of claims 11 to 16 wherein the modular controller comprises a means for interfacing with any one or more printers and/or radio-link data transfer systems and/or satellite navigation systems. 20 18. A method of manufacturing of explosives according to any one of claims 11 to o 17 wherein the modular controller comprises a robust, waterproof container.
19. A method of manufacturing explosives according to any one of claims 11 to 18 wherein the modular controller controls a fixed site manufacturing plant or a o 25 relocatable plant. A method of manufacturing explosives according to claim 19 wherein the relocatable plant is a mobile manufacturing unit or a unit for use underground. 3 21. A method of manufacturing explosives according to claim 19 or 20 wherein the modular controller controls the delivery of explosives from the delivery rate. P:\OPER\PHH\47978-96.RES 26/4/99 13
22. A me comprising: (a) (b) means; and (c) thod of calibrating the modular controller of any one of claims 1 to 9 feeding monitored process information into the memory means; having the data processor take the process information from the memory using a calibration factor, converting the process information.
23. A method of manufacturing and/or delivering explosives substantially as herein described with reference to the accompanying drawing and/or example. *as DATED this 26th day of April, 1999 ORICA AUSTRALIA PTY LTD By its Patent Attorneys DAVIES COLLISON CAVE SSSS S S S 5* 55O5 S S *S S
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