Laboratory instruments have a played a very significant role in the overall progress made by the cement industry in the last 25 years. From the classical method of analysis, to instrumental methods has been a long journey for the industry.
People of yesteryears who have been associated with the cement industry since the days of control are amazed to see how the laboratories of present cement plants are equipped. To list a few lab instruments which one could have only seen during those days in books are optical microscope, XRD and XRF, laser-based particle size analysers, cross belt analysers, coal analysers etc. Today all of these instruments are found in the QC lab of a cement plant.
Incidentally today?s integrated cement plant has more than just one laboratory, depending on the size and spread of the plant. There?s a main laboratory and the others are site laboratories. The site laboratory is generally close to the sample points and carries out only essential tests on the material that is in process. The samples are physically carried out or the modern plants use pneumatic devices to transport samples from sample collection points. It is a very tedious manual task to collect and carry the samples even in odd hours and during adverse climatic conditions. Therefore it is important to have a sample collecting device and a transportation system without involving human beings. One really does not know if the samples have been collected in the real sense or not, except that we have to trust the human beings involed in it. Till date there is no system to check the genuineness of samples collected by human beings. The quality of testing will depend on how representative the samples are. There are good number of occasions, when the results go wrong only due to faulty samples. As stated above, in modern plants, the collection of samples is done without human intervention and therefore the results are quite accurate and dependable. The second aspect is the time spent in analysis of samples, with use of latest generation of lab equipment. With instruments, testing is in real time and there is no lag experienced. What goes into process is analysed then and there itself and corrective steps are taken instantly. We must make a mention here of a few patented offerings by FLSmidth, QCX system is a quality control system and POLAB Shuttle laboratory automation system by ThyssenKrupp. These are state-of-the-art systems and readers can get more information from their respective websites.
The advent of computers and IT technology has made the job of a chemist much easier. Normally laboratories generate huge amount of data and with computers this data can be stored easily. If proper tools are used, analysis of data can improve the overall plant performance.
A Compressive Testing Machine (CTM) is an important lab equipment for measuring the strength of cement. In the present days with modern tools, strength testing data from CTMs is monitored and stored online to avoid any manipulation which otherwise was common in cement plants. At present, immediately during strength testing itself, the data is captured and reported or can be viewed from a distance.
A few of the latest plants that have been commissioned in the last three years are using robotics in their laboratory. This shows that the Indian cement industry is using best-in-class technology and is keeping pace with plants in the developed world. Coal is another grey area where lab instruments have a distinctive role. It is the material received in huge quantities and regularly tested in labs. Coal analysers have made the job simple, easy and transparent, which is the need of the hour. Data received is not only real-time but accurate also.
In the present issue we have covered only a few of the lab instruments which have found their effective use over a period of time in the laboratory. Let us examine a cross-belt analyser for bulk material analysis. Rajendra Mishra of PANalytical has given details right from the location where the instrument is installed to its usefulness. This device is present in almost all the plants now. The task of management from quarry to preparation of raw meal has been very easy since the introduction of cross belt analysers.
XRD and XRF are the most common instruments among the family of instruments and have been in use for a very long time. These analysers have scored over the old classical methods of analysis due to the simple reason that they are accurate and much faster than conventional methods. Among the articles we have included is provided by N L Deshpande of I R Technology who is representing Rigaku Corporation of Japan. The article gives details on trace analysis at ppm level in the shortest possible time. The same exercise if done by a conventional classical method will take days to complete and may not be that accurate. The standard samples created for analysis are extremely important in the overall exercise.
Cement being a fine powder, the measurement of fineness has been done by Blain air permeability apparatus for very long time. The fineness is expressed as the total area in square centimetres generated by a gram of cement powder. The test is indicative but not accurate. This gap has now been filled by particle analysers which are again very essential instruments for effective quality control. It is a laser based diffraction method. The difference is that it gives the size of particles in microns in predetermined range. Today cement technologists know what should be the range one has to keep for cement particles for getting the best strength out of cement.
Subsequently, one can set the parameters for the separators or grinding mills. You can read more in the article by Dr Michael Caves of Malvern AIMIIL. The advances have been so amazing that every new model of instrument becomes more user friendly than the earlier one.
The other area of lab instruments is portable lab instruments. These are mostly used either in the site lab or by the engineers who carry out process audits. One must appreciate that there are limitations to portable instruments because the main consideration is that the instrument must be portable. However as Sandeep Pillai has said in his article, these instruments are basically used for diagnostic purposes. These instruments should be consistent in producing results irrespective of place. Calibration at regular intervals is another requirement of portable instruments as stated by Pillai.