The long established, leading manufacturer of bulk handling equipment, Wrights Dowson Group, continue to manufacture and supply Screw Conveyors, Feeders and assorted bulk handling equipment from its factory in Gamlingay, Bedfordshire. Another facet of its all round capability came about during the 1980s, when Wrights Dowson identified a growing need for a controlled, traceable, quality assessment of a wide range of ‘in process’ bulk materials. In 1988 it resulted in the Wrights Dowson Group becoming a distributor for a major North American equipment manufacturer, InterSystems Inc., for their complete range of Industrial Samplers. This strong, continuing relationship between the two companies has enabled Wrights Dowson Group to build a global reputation along side InterSystems in the development and supply of powder, liquid and industrial automatic samplers across a broad swathe of industries.
This article sets out to explain the procedures surrounding the selection and use of automatic industrial samplers within one such global sector, Quarrying and Cement. The main issues covered are as follows:
•Sampling requirements.
•Sampling standards.
•Sampling methods
•Sampling equipment.
•New developments.
First, a brief explanation of automatic sampling, which is defined as the use of a mechanical device to remove a representative sample from a product flow and direct it either to a manual collection point or into an automatic collection cabinet. The auto collection system provides for pre set adjustable timers controlling the number or duration of samples. There is an inbuilt control flexibility that provides for a manual operation override and the facility to change the collection receptacle, type and quantity to suit specific applications.
Sampling Requirements
Once the sampling parameters have been determined and the equipment selection matched to the requirements, it is imperative that the user has confidence that the equipment is fit for purpose in three key areas:
•Representative Sample – That must be obtained at the same frequency by the same method and at the same location.
•Repeatable Sample – Where it becomes vital that the samples are collected in the same way at a predetermined time cycle.
•Reliable Sample– The quality of the sample is not only about representation and repeatability but the equipment is rugged, fit for purpose and can be easily operated and maintained.
Sampling Standards
Whilst this paper does not detail individual nation requirements, the reference to the ASTM standard is to highlight the fact that sampling of Cement and Aggregate has been defined by the Society in North America and has also been adopted by other countries, thereby providing a common quality assessment template. Naturally, there are alternative standards developed within trading zones such as the ISO in many parts of Europe or in individual countries where the state legislature or even weather patterns can impact on the sampling arrangements adopted but for the purpose of this study the standard followed is the ASTM.
For reference the ASTM standard defines the following sampling conditions:
Condition A = Stop Belt is a basic instruction that relates to the removal of a sample, manually or mechanically from a belt in a failsafe stop position.
Condition B = Crosscut – See detailed explanation below.
Condition C = Strip – See detailed explanation below.
Condition D = Quartering – Quartering is the least representative way to take a sample, this is an old method, which is rarely if ever used. The procedure was to take a front end loader scoop up some material from a product pile, dump the material on the ground, then a QC operator would take a section of the pile on the ground, assume it as being representative and endeavor to carry out an analysis confronted with all the vagaries of particle separation.
Thankfully, there are automatic options available and ASTM conditions B & C are fully met by the range of equipment supplied by InterSystems and the Wrights Dowson Group and the methodology used is explored in the following section.
Sampling Methods
When carrying out an investigating in the use of sampling, the Cement & Aggregates sector, like any industry are confronted with the issues of sampling requirements and the adoption of the requisite standards but determining the most suitable way to carry out the tasks develops within an industry over many years. The key points to be looked at, albeit briefly, are, to determine what materials are being processed and why are they being sampled, where is the most suitable location for sampling and by what specific method should the samples be obtained.
Typically, using Condition B = Crosscut will entail sampling being carried on belt conveyors for raw materials in quarries such as limestone etc, and in raw meal plant at gravity chutes, hoppers and spout locations. In conveyor terms, to meet the ASTM condition ‘B’, it is necessary to know the conveyor incline, belt width, belt speed and throughput, together with an awareness the factors listed below:
• Belts from 600mm (24’’) to 1800 mm (72’’).
• Mounted anywhere on the Belt.
• 35 degree Idlers.
• Sample Cutter (3 x std. Particle).
• Tip Speed 6.0m /sec (237’’ /sec).
It is worth noting that the sample cutter never touches the belt.
Fig. 1 below shows a sectioned drawing that outlines a typical belt sampler set up and shows the relativity of the key components, conveyor belt and the method of automatically directing the sample to collection.
In the Cement industry the ASTM ‘B’ condition also relates to use in gravity chutes and spouts and typically supports the sampling of raw meal. The InterSystems equipment widely specified in the industry is the type GRA/GRE cross cut sampler or a GRES derivative where sloping wall chutes are used. Again, Fig. 2 below details the features of the sampling system commonly used in gravity chute applications.
For an ASTM C = Strip sampling condition, the equipment is closely defined for use with clinker and finished cement with the samplers located in gravity spouts, pneumatic conveying lines, air slides and load out chutes both rail and truck and at belt ends. The operating specification allows for material sampling up to 75mm (3’’) the arm actuation is either by air or hydraulic control with a stroke range of 300mm –1370mm (12-54’’). The sample arm rotates through 270 degrees.
Sampling Equipment
Over the years as the technical, legal and operational aspects in industry have changed then the sampling equipment has correspondingly evolved and a one fits all culture has sharply reduced. It can be noted that a whole range of industrial samplers such as the types PS, PT, HD-PRT, PRT etc. are used for strip sampling whilst the GRS/GRE models cover the demand for cross cut sampling. Like the long standing InterSystems – Wrights Dowson Group relationship, the development of an understanding has led to a multi faceted approach to sampling problems and it is found that in most industries, including Cement & Aggregates, that inevitably where greater sophistication is a pre requisite a new solution is born. It is in striking this balance that the extensive range of InterSystems Inc, equipment comes to the fore.
New Developments
Naturally, like many other industries the aggregates and cement sector continues to be exposed to new technology, and developments in particle sampling and analysis are no exception. But, there is a question that must be raised, because it is relatively new, late 1990’s, and uses the latest in ultrasonic or shape analysis techniques, is it the complete answer? In Australia, the Materials Board has recently issued a standard, AS 1141.11.2 detailing the use of a Vision Sizing System (VSS) i.e. a high speed video camera linked to a computer, which ultimately provides a typical particle size distribution analysis in such a way that it produces comparable results to laboratory sieving. Vision sizing equipment installed at a major Quarry in New South Wales works in conjunction with a belt sampler operating to the Australian standard (AS 4433), which removes the required sample from the belt for electronic vision analysis. There is a written claim that the moisture content can also be obtained from a VSS but whether the chemical content and density is also obtained in the same way has still to be determined.
It appears to have taken a long time to move into the electronic era but still there is a requirement for an electro mechanical device like the InterSystems RS to present the sample. It is also a long way from the ASTM conditions for Quartering or Stopping a Belt to take a sample but innovation, in the VSS – Computer Analysis - Electro Mechanical Sampling will find a way, and it might not take 10 years.
With over 250 years of knowledge applied to solving industries problems the Wrights Dowson Group are proud of their history, the long term co-operation with InterSystems and the benefits to the customer that combined experience brings. They continue to invest in the future with the latest computer technology including advanced 3D design software, which provides their manufacturing facility, customers and potential customers with a service level of the highest order.
Samplers for Cement & Aggregates
Samplers for Cement & Aggregates
Wrights Dowson Group
Green End
Gamlingay
Sandy
Bedfordshire SG19 3LA
The long established, leading manufacturer of bulk handling equipment, Wrights Dowson Group, continue to manufacture and supply Screw Conveyors, Feeders and assorted bulk handling equipment from its factory in Gamlingay, Bedfordshire. Another facet of its all round capability came about during the 1980s, when Wrights Dowson identified a growing need for a controlled, traceable, quality assessment of a wide range of ‘in process’ bulk materials. In 1988 it resulted in the Wrights Dowson Group becoming a distributor for a major North American equipment manufacturer, InterSystems Inc., for their complete range of Industrial Samplers. This strong, continuing relationship between the two companies has enabled Wrights Dowson Group to build a global reputation along side InterSystems in the development and supply of powder, liquid and industrial automatic samplers across a broad swathe of industries.
This article sets out to explain the procedures surrounding the selection and use of automatic industrial samplers within one such global sector, Quarrying and Cement. The main issues covered are as follows:
•Sampling requirements.
•Sampling standards.
•Sampling methods
•Sampling equipment.
•New developments.
First, a brief explanation of automatic sampling, which is defined as the use of a mechanical device to remove a representative sample from a product flow and direct it either to a manual collection point or into an automatic collection cabinet. The auto collection system provides for pre set adjustable timers controlling the number or duration of samples. There is an inbuilt control flexibility that provides for a manual operation override and the facility to change the collection receptacle, type and quantity to suit specific applications.
Sampling Requirements
Once the sampling parameters have been determined and the equipment selection matched to the requirements, it is imperative that the user has confidence that the equipment is fit for purpose in three key areas:
•Representative Sample – That must be obtained at the same frequency by the same method and at the same location.
•Repeatable Sample – Where it becomes vital that the samples are collected in the same way at a predetermined time cycle.
•Reliable Sample– The quality of the sample is not only about representation and repeatability but the equipment is rugged, fit for purpose and can be easily operated and maintained.
Sampling Standards
Whilst this paper does not detail individual nation requirements, the reference to the ASTM standard is to highlight the fact that sampling of Cement and Aggregate has been defined by the Society in North America and has also been adopted by other countries, thereby providing a common quality assessment template. Naturally, there are alternative standards developed within trading zones such as the ISO in many parts of Europe or in individual countries where the state legislature or even weather patterns can impact on the sampling arrangements adopted but for the purpose of this study the standard followed is the ASTM.
For reference the ASTM standard defines the following sampling conditions:
Condition A = Stop Belt is a basic instruction that relates to the removal of a sample, manually or mechanically from a belt in a failsafe stop position.
Condition B = Crosscut – See detailed explanation below.
Condition C = Strip – See detailed explanation below.
Condition D = Quartering – Quartering is the least representative way to take a sample, this is an old method, which is rarely if ever used. The procedure was to take a front end loader scoop up some material from a product pile, dump the material on the ground, then a QC operator would take a section of the pile on the ground, assume it as being representative and endeavor to carry out an analysis confronted with all the vagaries of particle separation.
Thankfully, there are automatic options available and ASTM conditions B & C are fully met by the range of equipment supplied by InterSystems and the Wrights Dowson Group and the methodology used is explored in the following section.
Sampling Methods
When carrying out an investigating in the use of sampling, the Cement & Aggregates sector, like any industry are confronted with the issues of sampling requirements and the adoption of the requisite standards but determining the most suitable way to carry out the tasks develops within an industry over many years. The key points to be looked at, albeit briefly, are, to determine what materials are being processed and why are they being sampled, where is the most suitable location for sampling and by what specific method should the samples be obtained.
Typically, using Condition B = Crosscut will entail sampling being carried on belt conveyors for raw materials in quarries such as limestone etc, and in raw meal plant at gravity chutes, hoppers and spout locations. In conveyor terms, to meet the ASTM condition ‘B’, it is necessary to know the conveyor incline, belt width, belt speed and throughput, together with an awareness the factors listed below:
• Belts from 600mm (24’’) to 1800 mm (72’’).
• Mounted anywhere on the Belt.
• 35 degree Idlers.
• Sample Cutter (3 x std. Particle).
• Tip Speed 6.0m /sec (237’’ /sec).
It is worth noting that the sample cutter never touches the belt.
Fig. 1 below shows a sectioned drawing that outlines a typical belt sampler set up and shows the relativity of the key components, conveyor belt and the method of automatically directing the sample to collection.
In the Cement industry the ASTM ‘B’ condition also relates to use in gravity chutes and spouts and typically supports the sampling of raw meal. The InterSystems equipment widely specified in the industry is the type GRA/GRE cross cut sampler or a GRES derivative where sloping wall chutes are used. Again, Fig. 2 below details the features of the sampling system commonly used in gravity chute applications.
For an ASTM C = Strip sampling condition, the equipment is closely defined for use with clinker and finished cement with the samplers located in gravity spouts, pneumatic conveying lines, air slides and load out chutes both rail and truck and at belt ends. The operating specification allows for material sampling up to 75mm (3’’) the arm actuation is either by air or hydraulic control with a stroke range of 300mm –1370mm (12-54’’). The sample arm rotates through 270 degrees.
Sampling Equipment
Over the years as the technical, legal and operational aspects in industry have changed then the sampling equipment has correspondingly evolved and a one fits all culture has sharply reduced. It can be noted that a whole range of industrial samplers such as the types PS, PT, HD-PRT, PRT etc. are used for strip sampling whilst the GRS/GRE models cover the demand for cross cut sampling. Like the long standing InterSystems – Wrights Dowson Group relationship, the development of an understanding has led to a multi faceted approach to sampling problems and it is found that in most industries, including Cement & Aggregates, that inevitably where greater sophistication is a pre requisite a new solution is born. It is in striking this balance that the extensive range of InterSystems Inc, equipment comes to the fore.
New Developments
Naturally, like many other industries the aggregates and cement sector continues to be exposed to new technology, and developments in particle sampling and analysis are no exception. But, there is a question that must be raised, because it is relatively new, late 1990’s, and uses the latest in ultrasonic or shape analysis techniques, is it the complete answer? In Australia, the Materials Board has recently issued a standard, AS 1141.11.2 detailing the use of a Vision Sizing System (VSS) i.e. a high speed video camera linked to a computer, which ultimately provides a typical particle size distribution analysis in such a way that it produces comparable results to laboratory sieving. Vision sizing equipment installed at a major Quarry in New South Wales works in conjunction with a belt sampler operating to the Australian standard (AS 4433), which removes the required sample from the belt for electronic vision analysis. There is a written claim that the moisture content can also be obtained from a VSS but whether the chemical content and density is also obtained in the same way has still to be determined.
It appears to have taken a long time to move into the electronic era but still there is a requirement for an electro mechanical device like the InterSystems RS to present the sample. It is also a long way from the ASTM conditions for Quartering or Stopping a Belt to take a sample but innovation, in the VSS – Computer Analysis - Electro Mechanical Sampling will find a way, and it might not take 10 years.
With over 250 years of knowledge applied to solving industries problems the Wrights Dowson Group are proud of their history, the long term co-operation with InterSystems and the benefits to the customer that combined experience brings. They continue to invest in the future with the latest computer technology including advanced 3D design software, which provides their manufacturing facility, customers and potential customers with a service level of the highest order.
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