Keeping track of product quality with Scantech International
Scantech is a renowned provider of process control solutions for bulk materials.
The wide range of available technologies and control software ensures that the right solution is chosen in each application. The company’s products include solutions for the coal industry, power plants, minerals, cement and steel. It also offers expertise in the monitoring of real time moisture content of conveyed materials.
Scantech is an ideal partner for plants where output may be increasing, but quality assurance is struggling to keep up. Operators must meet product specifications with cost-effective process control, with the scalability to keep plants operating efficiently and effectively. Scantech’s process control solutions deliver what’s needed. In fact, more coal is monitored each day by Scantech’s process control solutions, than by all other companies combined.
The wide range of online analyser technologies available ensures that the right instrument is selected as part of each site’s individual solution.Alongside our analyser technology we have developed our own user friendly display and process control software. This ensures complete process control solutions.
Notable among its products are: y COALSCAN: historically the COALSCAN has been Scantech’s
flagship;
  • Geoscan: the Geoscan is an on- belt elemental analysis system for monitoring bulk materials such as limestone and iron ore;
  • TBM200: the TBM200 series of moisture monitors are the result of Scantech’s many years of experience developing microwave technology;
  • CM100: the CM100 coke moisture monitor is a direct, on- conveyor monitor for measuring moisture in conductive materials;
  • CIFA350: the Carbon in Fly Ash Monitor provides significant benefits to coal fired power stations; and
  • NG Minerals Monitor: Model 1500 Natural Gamma Minerals Monitor.
  • This article will focus on Scantech International’s flagship product COALSCAN. COALSCAN is available in a range of configurations.
COALSCAN 2100
The COALSCAN 2100 is a new configuration in the Dual Energy Transmission (DUET) ash gauges and offers all the accumulated operational experience gained since COALSCANs were first developed, but at a significantly reduced price.
Scantech has been supplying DUET technology for many years now and these systems have proven to be the most popular of the COALSCAN range. The optional superSCAN output display system is available or
the information from the monitor may be input directly to the plant process control system. The very high speed response of the COALSCAN 2100 makes it suitable for such applications as sorting and run of mine monitoring, as well as product monitoring. As well as building on Scantech’s worldwide reputation for reliability, the new generation of COALSCAN 2100s are also amongst the easiest to operate and easiest to afford.
An earlier model of the COALSCAN 2100 was the COALSCAN 2500.
 
COALSCAN 2800
The COALSCAN Model 2800 is one of the Model 2000 Series ash and moisture monitors.
The analyser includes both gamma ray and microwave absorption techniques in a single integrated enclosure for the measurement of ash and moisture. These two measurements allow a calculation of calorific value.
These instantaneous measurements can be further integrated for output over a user configurable period eg shift, stockpile etc. The optional superSCAN output display system is available to carry out this task or the information from the monitor may be input directly to the plant control system. Scantech’s application of gamma ray technology, known as Dual Energy Transmission (DUET), is the most accurate application of this technology commercially available.
 
COALSCAN 9500X
The COALSCAN 9500X is an on-belt elemental analyser for coal.
The COALSCAN 9500X utilizes a combination of analysis techniques to monitor a wide range of coal parameters. These techniques include Prompt Gamma Neutron Activation Analysis (PGNAA) to determine the elements and ash content and a microwave moisture analyser.
The COALSCAN 9500X provides continuous monitoring of the standard coal analyses ash, sulphur, specific energy/heating value and moisture.
In addition, the COALSCAN 9500X can monitor and report the major oxides in ash, such as: SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, K2O,TiO2, MnO2, SO3, and Cl depending on concentration.
The COALSCAN 9500X has been engineered as a compact, fully integrated, single enclosure measurement unit which is installed on the conveyor and monitors the full flow of coal.
The calibration process uses a patented technique that accounts for variations in bed depth and moisture content to provide accurate measurement of ash, moisture, sulphur and other elemental constituents of coal.
 
COALSCAN 1500
The COALSCAN 1500 is an economical on-line ash monitoring system which is easily installed directly under production conveyor belts.
The major features of the COALSCAN 1500 include:
  • easy installallation and simple operation;
  • no radiation sources — no requirement for licensing;
  • underbelt configuration — suitable for raw coal and high tonnage applications;
  • fully automatic operation — no operator intervention
  • required; y no mechanical moving parts — low maintenance costs;
  • automatic electronic stability checks — drift-free performance;
  • no operational upper limit to coal size or coal bed depth;
  • flexible system interface to suit specific site requirements; y non contact technique — no high wear components; y superior total cost of ownership; and y designed for long product lifecycle.
 
This same technology is available for gold applications (GOLDSCAN), sugar cane applications (CANESCAN) and iron ore applications (IRONSCAN).
 
 
Liquefaction and the risk of disaster
It is one of the most pressing matters currently on the agenda of shippers, ship owners, Protection and Indemnity clubs, hull and cargo insurers, international regulatory organizations and inspection companies – flow moisture testing and the dangers of ships capsizing.
At the heart of it is the problem of liquefaction, that is, the potential for a dry cargo to turn into a semi- liquid state. The consequences can be tragic and besides the material loss of a ship and its cargo can also lead to loss of life if cargoes assume this condition on the high seas. It does not take too much imagination to think of the instability caused if for instance a cargo of nickel ore suddenly takes on this liquid state. Capsizing becomes a real possibility (with very little warning). Indeed, for various market reasons, there has been an increasing regularity of such disasters (including loss of life) since 2010. And even where actual capsize is averted, the financial consequences of a vessel not being allowed to sail (or having to divert after sailing) can be enormous and reverberate throughout a long chain of parties interested in both vessel and cargo.
The Commodities Trade Division of Bureau Veritas, ‘Inspectorate’ is at the forefront of mechanical testing expertise. This is deployed so that all affected parties can make informed decisions about the safety of materials to be loaded. In particular Inspectorate is continually developing its capability in respect of the measurement of the Flow Moisture Point (FMP) and Transportable Moisture Level (TML) which by calculation builds in head room as a precautionary measure.
Of utmost importance to Inspectorate is a relentless, single- minded drive for consistency across all international laboratories that offer such testing.
Liquefaction is an area fraught with difficulty for all parties. The effect is most obvious in fine particle commodities such as iron and nickel ore, copper and zinc concentrate.
The process of liquefaction can occur through vibration and motion forces during shipping. This can cause the space between particles to contract and compress free water in those spaces. This can impact on the cargo by reducing the frictional force between the particles by acting as a lubricant potentially allowing the cargo to flow. It is friction that normally keeps the cargo in a solid state.
When the moisture levels in the cargo are too high, liquefaction can occur even if the cargo appeared dry when loaded.
There is now a strong drive to improve knowledge of this danger in ports across the world. In 2011 the International Maritime Organization (IMO) Safety Committee commissioned its Sub-Committee on Dangerous Goods, Solid Cargoes and Containers (DSC) with a remit to “develop a scheme for ensuring reliable independent sampling and testing and certification of cargoes; and education for ship and shore personnel involved with the shipment of dry bulk cargoes with an emphasis on accurate cargo declarations to ensure safe cargo is loaded’. Up to this time the shipper has an obligation to provide this declaration.
Inspectorate is fully supportive of this drive. It does so, on the basis of its extensive knowledge, particularly from its work in India and Indonesia. In 2011 it conducted more than 700 FMP tests, the majority (but not exclusively) of which were carried out in these two countries.
Nickel ore which has liquefied in the hold.
Testing is rigorous and involves a number of steps.The ‘Flow Table Test’ used to determine the FMP and hence TML, as described in ISO 12742, is a technique recognized by IMO.These tests simulate the conditions which a cargo might experience whilst being shipped and gives a measure of a given commodity’s potential to liquefy.
Another crucial component is the accurate determination of the inherent moisture, both of the stockpile and when the cargo is loaded. Presented with the data for TML and moisture, port authorities and shippers must decide that the cargo is safe to ship. But — and this is the critical point — before he sails the Master must be confident that the bulk cargo has been rigorously subjected to any necessary liquefaction test.
Sampling presents all parties with significant challenges. One of the most important is achieving representative samples to ensure the most accurate results are possible and the true potential to liquefy during transit is thoroughly understood. There are inherent difficulties in sampling stockpiles and it is important that all parties work closely together to ensure the sample taken is as representative of the whole cargo as is possible. Stockpiles with mixed grades of ore add further to the sampling difficulties. Another factor to be considered is the maximum particle size. The Flow Table Test excludes particles that are greater than 7mm. It is important that the moisture level is determined from samples where the maximum particle size is no more than 7mm; otherwise results could misleadingly indicate safe moisture levels. Where stockpiles contain particles greater than 7mm then it will be necessary to follow procedures as laid down by the port authority.
Inspectorate has rigorous internal standard operating procedures and Keith Blaxall, Inspectorate’s global technical director and his team lead a stringent internal accreditation scheme to maintain a consistent service across all its facilities.
At the same time it continues to work on its own and with others in the industry to improve the testing methods.
More than this, Inspectorate seeks opportunities to increase knowledge and understanding of the liquefaction problem.
While Inspectorate provides rigorous results it is important that users should understand the limitations of those results. The final decision on whether it is safe to ship a cargo must be based on a range of information of which the TML and moisture level is important but not definitive.
 
 
Sampling based on modern sampling theory
Alex Stewart International employs more than 1,200 people in over 45 countries and operates 17 laboratories, write Mr. Graham Stewart and Mr. Kozo Matsumoto, Alex Stewart International Corporation. Alex Stewart International provides its customers with independent verification of the quantity and quality of bulk commodity shipments, as well as geochemical analysis of mining samples for exploration projects. Core business services are for large international commodity trading companies within the agriculture, metals and mineral and oils and petroleum industries.
As a service company, one of Alex Stewart International’s core business areas is the supervision of weighing and sampling of base-metal concentrates, where the company considers it most important to rely on modern sampling theory, not on rule- of-thumb.
Total sampling variance is defined as:
  • Primary variance of primary increments divided by the number of primary increments;
  • + sample preparation variance + analytical variance divided by the number of replicate analyses.
In order to design any sampling scheme, first it is important
to decide the target value of the total sampling variance. Then a decision must be made on: primary variance of
primary increments; sample preparation variance; and analysis variance.
Here, in fact in modern theory, there are two schools of thought;
  • P. Gy’s theory using the concept of variogram; and
  • traditional theory stemmed from some of JIS standards.
Traditional sampling theory is based on the assumptions that each sampling point is statistically independent of all others and that analysis results at each point are subject to a normal standard distribution.
If this is not deemed to be the case, then it is better to follow Gy’s theory.
Following Gy’s theory, the required number of sample increments for each lot tends to be much less than the one established by traditional theory. However, at Alex Stewart International, it is believed that the truth lies in- between both theories and that considerable experience in actual shipments is vital.
Also, in actual shipments, correct determination of moisture content of any bulk cargo is extremely important. This point would seem self-evident, but in reality, contrary to expectation, it is rarely carried out at the loading point. Alex Stewart has considerable experience in this throughout the world.
Lastly, it should be emphasized that normally taking many samples will not resolve any sampling issues. Too many samples can create other serious difficulties in sample reduction. This issue will also have to be resolved based on theory and experience.