Coal Mining - Science topic

GOOD QUESTION！

All details about FLAC3D including geometry can be found in Users' MAnual. You can also try F2F (build the geometry with meshing in Phase2) or FLAC2D with intrusion option then export to 3D). Unfortunately you have to practice. Step-by-step videos can be found in Youtube

My advise is firstly, to build the model as simple as possible and then correct the model details (mine roadways, gobs, the powered roof support, etc) due to the actual conditions

here are some examples for you to check out

1. Numerical Investigation of Roof Stability in Longwall Face Developed in Shallow Depth under Weak Geological Conditions

2. An investigation of longwall failure using 3D numerical modelling – A case study at a copper mine

Good luck

Any power source used in a hazardous environment would need to go through appropriate approvals before it is used in the specified environment.

Large capacity cells produce a challenge when the short circuit current, in an untoward event, would exceed the required heat limits. You may have to work with your certification agency like ATEX (UK) to ensure the operation is redundantly safe.

Yes, we have just data from China.

Dear Manisha,

thank you for posting this. I am wondering to whom exactly the author of this article is referring to when talking about "Germany" (as in: "Germany portrays itself as [...]") - the people of Germany (> 80 mio.!), the present federal government, the last federal government, the ruling three parties ("traffic light coalition"), the government of NRW (where much of this story is situated)? I could go on and on.... I realize that journalists are always after a catchy headline. But sometimes the real world out there is FAR more complex than a headline suggests...

Respectfully from Berlin,

Julius

Have you tried the search function in ResearchGate for publications?

Scrolling down a few responses yields several coal dust specific references.

Zymogenous microbial proliferation are more in post mining sites. I think a new area of research could be to study the nutrient dynamics (microbial transformation) of Zn, Fe, Mn etc. With various oxidising microbes.

Roof garden and green wall both equally contribute to mitigate dust pollution.

Many thanks for your answers. My best regards, Joseph

For the repose angle and bulk density is not difficult. From a little conic pile, you can measure the perimeter, calculate the radius; measure the height and than calculate the angle. There are in literature some ways to determine bulk density. See:

Lopez, J.; Vercik, A.; Costa, E.J.X. Meios granulares e experimentos simples para a sala de aula. Rev. Brasileira de Ensino de Física, v.30, n.1. 2008.

Lopez, J.; Demarchi, T.; Akamatsu, M.; Vercik, A. Estudo comparativo de algumas propriedades dinâmicas de líquidos e grãos na sala de aula. Revista Brasileira de Ensino de Física, v.32, n.1. 2010.

Here is the virtual sieving. Differential sieving is shown in red. When summing up all the columns, you get 100%. The blue line represents the cumulative distribution. X-axis dimensions are in logarithmic scale. The data in the window in the upper left corner mean: Cu - Coefficient of Uniformity = D60/D10, a measure of the slope of the cumulative weight % curve between the 60- and 10-percentiles. Dn - Nominal diameter, or equivalent spherical diameter, i.e. the diameter of a sphere with the same volume as that computed for the fragment. D10, D25 etc. - Percentile sizes. For example D10 is the ten-percentile, the value of De for which 10% by weight of the sample is finer and 90% coarser. In terms of sieving, D10 is the size of sieve opening through which 10% by weight of the sample would pass. D50 - The Median or 50-percentile, the value of Dn for which half the sample weight is finer and half coarser. Blocks - Number of net elements detected in the NET image. Max - Maximum size of fragment in the image [Dn (m)]. Mean - Arithmetic mean (average) fragment size, equal to the sum of all equivalent spherical diameters divided by the total number of particles [Dav (m)]. Min - Minimum size of fragment in the image [Dn (m)]. Mode - Most common sized particle, the geometric mean Dn size class interval for the class containing the greatest number of net elements (fragments) [Dn (m)]. N - Rosin-Rammler (and Gaudin-Schuhman) Uniformity Coefficient, equal to the slope of the Rosin-Rammler straight line fitted to the data in log-log coordinates. Sphericity Dn/Ds, the ratio of equivalent spherical diameter to the diameter of a circumscribing sphere (long axis of the fragment). stdev - Standard deviation of fragment size Dav. Xc - Characteristic Size, the intercept of the Rosin-Rammler straight line fitted to the WipFrag Dn data in log-log co-ordinates. This is equivalent to the D63.2. Xmax - Gaudin-Schuhman characteristic size, the intercept of the 100 % passing and the slope of the Gaudin-Schuman straight line. If you have any questions, write to me! Good luck!

https://www.catallday.com/articles/challenges/worksite-productivity/bucket-fill-factors

Profitability of RE extraction is commercial in confidence - that means, only the organisations doing the work will have accurate figures. Do you have all the chemical steps and stages for your extraction process? Do you have figures for their costs? This is going to be a major task, but best wishes for your work!

All of these advances inevitably led to the assumption that new resources were not needed in the development process. This is due to the fact that based on fossil fuels - on the other hand.In reality, this contrast is far from straightforward and requires more thoughtful study. Carbon dioxide capture and storage (CCS) and methane management technologies at all stages of the increment in the cost of energy from fossil sources can help fulfill large-scale tasks to reduce CO2 emissions while fossil fuels are still part of the energy system. Thus, these measures allow fossil fuels to become part of the solution, rather than remain part of the problem. A rational economy plays an important role in the energy systems of each technology.

Testing of mine water is needed and accordingly online filter and online anti-corrosive additive can be added.

Dear Ali Ejaz Qureshi .

I am very glad that you are working in this direction.

I am also engaged in the optimization of technological schemes for coal mines with low-power seams.

In Ukraine, the thickness of most layers is 0.8-1.2 m.

Here is a link to my work

A new article on optimizing process diagrams is coming soon.

Here is the link to my Google Scholar profile https://scholar.google.com.ua/citations?user=ebUy32AAAAAJ&hl=ru

I can advise the work of such authors:

Mamaikin Aleksandr https://scholar.google.com.ua/citations?user=Az94xCoAAAAJ&hl=ru

Salli Serhii https://scholar.google.com.ua/citations?user=zBih2qwAAAAJ&hl=ru

Fomychov Vadym https://scholar.google.com.ua/citations?user=CSEHSaAAAAAJ&hl=ru

Look magazine Mininh of Mineral Deposits http://mining.in.ua

I'll be glad to help. Here is my mail khorolskiyaa@ukr.net

Good luck

Adel Badri but the paper is related coal combustion but I need emission rate from coal mines Sir.

Now a day the numerical analysis offer many simulations of mining technologies used in mining practices. My recommend is if you use sophisticated numerical analysis than check results with adequate in situ measurements.

I believe that the coal mine industry have been moved from the west to the east, to countries where HSE prevention is not a main priority of the companies.

If the question is about the west, I remember to seeing statistics on the increase of silicosis in the ornamental stone industry with the new products of aggregates, and the workers of these kind of companies than work cutting these materials

Dear Pavel,

Always open to cooperation.

My e-mail: khorolskiyaa@ukr.net or additional e-mail: andreykh918@gmail.com.

Regards.

Andrii

According to a research the groundwater quality decreases with depth.Groundwater flowing through abandoned coal mines often has depressed pH levels and elevated hydrogen sulphide, iron, aluminium and nitrates.

Such water is also typically high in copper, zinc, mercury, and lead. Impacts of hydrogen sulphide in drinking water yet hydrogen sulphide is

commonly found in the groundwater near coal mines. This gas is known to cause detrimental respiratory illness in humans.However, the systemic effects of ingesting hydrogen sulphide are obscure, and studies correlating hydrogen sulphide to health have been restricted to lab animals.

Dear colleague that textbook may help you to differentiate trace elements and their occurence in coal mine (Swaine, D. J. (1991). Trace Elements in Coal.

As long as the measurement is made from near the truck, just about any lidar should be capable of such a simple measurement. In fact, I'd look into passive imaging methods that would be simpler, with lower cost.

Sunny,

It has lot of good information and helped me a lot for pillar design.

Thank you

Two aspects to be considered with regard to subsidence is the information of sub-surface geological formation (mainly the clay seams) and the hydraulic pressure of groundwater (artesian / confined condition).

Please get soil samples sieved with < 0.2 mm diameter; this may possibly eliminate coal carbon from soil OC. It is expected that coal C may have diameter > 0.2 mm. Just try.

Distortion power is not captured in vertical transportatio, reason being it may be very momentary and also under dynamic situations.very less.

As mentioned by professor Mircevski we measure S(Kva) and Q ( kvar) , the source need to be identified and corrective actions to be implemented

For stable isotopes hydrology (deuterium and Oxigen 10) see refferences:

 For coal mine impact assessment of groundwater regime see refference:

What makes underground coal mining stand out from most other industrial environments is the capacity for disasters involving multiple fatalities. In Queensland underground coal mines, there have been 90 fatalities since 1970. Of these 90, two-thirds or 60 were the result of multiple fatality accidents. Incidents that have resulted in multiple fatalities in Queensland mines include  fires, gas explosions, gas poisoning and large scale rock falls. In other jurisdictions flooding has also caused several accidents. This is usually due to breaking through into old abandoned workings as at Gretley Mine in New South Wales in 1996, at the Porter Tunnel in Pennsylvania in 1976 and Lofthouse mine in the UK in 1973. It is noteworthy that at Moura number 2 Mine in Queensland in July 1994, management closed the entire mine for two days and engaged all employees in an intensive workshop to analyse the risks at the mine and propose defensive measures. The result was a 70 page report covering many items - but conspicuously .missing from the analysis was a gas explosion ignited by spontaneous combustion.  Just a few weeks later an explosion ignited by spontaneous combustion in a sealed off area of the mine resulted in 11 deaths and closure of the mine. In my opinion, analysis of risks in underground coal mining should always give top priority to the possibilities for disaster,. and never ever dismiss them as "low probability". In many accidents including Moura, management and employees were well aware of the risks and the means to mitigate them, but through long exposure had become blase. An important component of any safety program is an inspection and quality control program to ensure mitigation measures are properly and thoroughly implemented.

As the band intervals are different for different Landsat Satellites the calculated NDVI will be effected based on these differences. For example, lower vegetated areas has higher NDVI values with Landsat 8 than Landsat 7. About this issue, you can check these articles:

Compare NDVI extracted from Landsat 8 imagery with that from Landsat 7 imagery

Comparison of the Continuity of Vegetation Indices Derived from Landsat 8 OLI and Landsat 7 ETM+ Data among Different Vegetation Types

On the other hand, what do you want to achieve by measuring vegetation growth? As I understand you want to use only 1 imager per year. If so you can use change detection techniques in order to show the vegetation growth over mined areas.

And occasionally manufacturers go through a trend of differentiation such as the use of a "white wall" (decorative contrast color applied to the side surface of the tire). These were quite stylish on early Buicks etc. I think any manufacturer who tried to bring back a white wall tire today would be ridiculed.

 Spatial-Temporal Data Mining, for example:

https://www.researchgate.net/publication/311899839_Control_and_minimization_of_allergenic_plants_impact_on_bronchial_asthma_morbidity_based_on_spatial-temporal_data_model?_iepl%5BviewId%5D=5NqdAcXIqrDYqiEO3uGY1smw&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BinteractionType%5D=publicationTitle 

Kindly have a check on following..

i agree with Rafael Anleu  

For  soil N-15 samples, i just dry and gried them as they are without any decalcification or acidification procedure.  After that, i send soil samples for IRMS (Isotope-ratio mass spectrometry) analysed and basically that's it.

Hope it helps you

Dear Bibhu

I'm really a placer gold mineral separation expert, not coal.

I suggest the silica sand would be recovered by either gravitational settling (eg jig or pan or sluice) or by surfactant floatation.

Robin

No silver bullet in geophysical techniques generally.  It very much depends upon the surface and depth to the adit.  If the adit is under the water table and relatively shallow (sy 10m or so) then I'd suggest an EM survey (EM-31 or EM-34 for example).  Geoelectrical surveys such as resistivity and IP may be useful wrt acid mine activity; however, interpreting such data can be very, very difficult.  The cobble-boulder overburden sounds a bit odd.  The most effective means I know of to find a water filled tunnel or such is to use misse-a-la-masse or similar with a magnetometer (MMR method).  The techniques places an electric current into the tunnel and another electrode far away.  The electric current tends to follow the tunnel water out towards the far electrode.  The surface electric field or magnetic field (measure the difference between current on and then off to remove background fields) indicate the presence and extent of current flow..  I have used such techniques in mapping tree root zones and with an UG research project to find water channelling near bridge supports during flooding - usually hopeless targets with conventional geophysical tools. Modern adaptations of the idea are used in "pipe finder" tools used by engineers to find buried pipes in industrial areas with a lot of other buried clutter.    

no manufacture publishes prices for the reasons of being undercut by competitors.

If you go to Scaw Metals website you will find a brochure of all types and sizes of rope. You will then have to contact them for indicative prices.

DF]S14080 Shaft Mining Brochure Tail Ropes WEB - Scaw Metals Group

Indirect method can never be a substitute for the direct method however, from a coal sample after preparing a core  and after having proximate analysis and adsorption isotherm values the Kim's formula can be used. One may find the results with significant level of uncertainty.

Roof depends on the combination of factors .You can read the paper of Smith, A. D. and also of Mark & Molinda for your quarry. Hope you will find answer.

1. Mine Roof Condition and the Occurrence of

Roof Falls in Coal Mines

Smith, A. D.

The Ohio Journal of Science. v84, n3 (June, 1984), 133-138

2. The Coal Mine Roof Rating in Mining Engineering

Practice by C. Mark & G. M. Molinda 2003 University of Wollongong

Research Online

However, I would like to mention that one single discontinuity  (especially sub-horizotal to horizontal) if not identified during exploration , in rock mass may override all calculations based on general rating.

Dear Toribio,

I visited on of the highly reducing lake in Iraqi Kurdistan, northern Iraq. It is not an active coal mining but it can help to get general geological and environmental setting for reducing environment and studying bio activity within this kind of environment.

we have some papers on mining waste land development

may be useful to you as a application.

Increase the size and do several parametric study to ensure the stress distribution doesn't change with the model size. 

I recently found this paper which might contain some useful references:

Yu, Vozoff and Durney: The influence of confining pressure and water saturation on dynamic elastic properties of some Permian coals, Geophysics 58 (1993) 30-38

Area of exposure gives a volumetric sense and area of roof exposure gives a geometric sense.

it means any place or point which is exposed to the under ground environment is included in area of exposure and  area of roof exposure is also an exposed area but restrict only upto the roof.

The main cause of this problem is the incorrect ventilation design during pre-feasibility/feasibility study stage. Ventilation design in a longwall mine depends solely on Specific Gas Emission (SGE), which is the amount of seam gas liberated per tonne of coal mined in a longwall panel (m3/tonne). The seam gas is usually methane, but few mines in Australia have carbon dioxide as the predominant seam gas. The main issue in calculating SGE is that most of the gases (around 90%) come from seams above and below the mined seam (remote seams), and it is extremely difficult to estimate contribution from each remote seam due to many unknown factors, such as the extend of these seams that is fractured by longwall caving, virgin gas content of each of these seams, and the amount of gas liberated by each remote seam (which is a function of ground water pressure). There are many models to estimate SGE but all of them use assumptions to cover the unknown factors described before. Experience in Australia found that they usually underestimate SGE (which subsequently underestimate the amount of airflow and gas drainage), so engineers usually apply a correction factor of 1.5 to the output of these models. Modelling SGE remains a main problem in designing ventilation in longwall mines up to this day.

Increasing air velocity in longwall face has a limitation, in which that the air velocity at the face has to be kept below 5 m/s in order to keep personnel comfortable and to prevent dust stirred up from the floor. For example, if the longwall face cross sectional dimension is 5 m wide and 4 m high, then the maximum airflow that can be delivered in the face is 100 m3/s. Probably the limit can be increased to 6 m/s if a very good dust suppression system is installed. In this case, the maximum airflow is 120 m3/s. The point is that you can only increase the airflow to a certain limit due to the air velocity limit at the face.

In gassy mines in Australia, ventilation alone is not adequate to control methane and carbon dioxide in return airways. Therefore, extensive gas drainage is used (pre-drainage and goaf drainage). In these mines, 60 to 80% of SGE is taken by gas drainage. Of course the caveat is cost as gas drainage is very expensive. Few mines recoup some of this cost by selling methane to generate electricity.

Bleeder airways are not used in Australia due to Spontaneous Combustion. Moreover, bleeder causes oxygen concentration in the goaf to be greater than 12%. In this situation, explosive mixture is formed (5 to 15% methane and oxygen 12 to 19%), which is very dangerous and should be avoided at the first place. These are the reasons of why I'm not a fan of using bleeder airways

Therefore, the answer to your question is first, you increase the airflow in the longwall face until the air velocity reach 5 m/s. If this doesn't work, then you will need goaf drainage, and probably in-seam pre-drainage. To desigh the drainage plant (capacity), you will have to work out SGE. I can give you a model (set of calculations) that I believe is quite accurate if you want to. Just give me your email address and I'll send it to you.

I agree with Prof.Gloaguen. If the data is not matched with your objectives, kindly change it. Or try data fusion with optical data.

If you solely use the RADARSAT data, you may add textural features or decomposition methods to improve the classification. There are some methods that can help you for better spectral seperability. You may check the article below:

Effect of Different Target Decomposition Techniques on Classification Accuracy for Polarimetric SAR Data

I also suggest you to analyse the data spectral response and training data characteristic. You may define the methods more proper up to the result of it.  

See this article as well.

Haack BN, Khatiwada G; Comparison and integration of optical and quadpolarization radar imagery for land cover/use delineation. J. Appl. Remote Sens. 0001;4(1):043507-043507-16.

Your question is intriguing and also needs to be addressed from practical and visual investigations as well, which provide some wonderful signs of impending dangers. Roof falls are major concern for any underground mining professional. It may be interesting to note that several hours before a major fall in one of the UG coal mines, we could hear very low intensity noise from the roof before its final collapse. Also, many times by tapping the roof with an overman's wooden rod, the roof gives a husky sound instead of its characteristic sharp sound. The sides may show the signs of spalling. Also, many a times, I could witness sudden increase in water seepage from roof. Supports (timber) were also observed to buckle.

Coming to your concerns, if RMR rating is high, we can go for expansion in roof exposure area with a limited confidence,though. Cover depth definitely enhances the chance of roof fall. Hence, we need to strike an optimization among cover depth, RMR rating and the span or maximum exposure area.

Furthermore, the borehole logs of the districts, if available, should be thoroughly scrutinized for studying the nature of immediate roof layers. Acoustic emissions from the roof need to be also studied. Also, wherever possible the convergence recorders should be used in addition to seismic studies.

Utilization efficiency of coal resources begins with efficient recovery of mineable coal reserves from underground/open-cast  mines.Thereafter,  effective utilization of recovered coal in surface plants like Coal Handling Plants (CHP), washing plants (washeries) etc also needs to be considered;in some cases even the middlings and tailings from the washeries are re-used in power generation. Then for the thermal coals, the ash utilization also adds to the coal resource recovery efficiency.

The utilization efficiency of land resources implies that what percentage of land, environment and ecology that was disturbed due to coal mining has been restored/ reclaimed or even upgraded in comparison to its original topography. 

Ideally the ratio between the two should be 1:1.

With increase in height the pillars become less stiff and more flexible to spalling or breakage. This, in turn, increases the chances of roof failure and falls.

Dear Mohammadi, The answer for your question is Hydro - Borehole Mining technology

details , please contact me by e-mail w.jura@wp.pl

Regards W.Jura 

Many thanks!

Dear Dr. Johannes.

I sent a brief information of the explosion of the San Fernando coal mine in Amaga Antioquia Colombia. In coal mining Colombian  we have problems in the operation and safety mining. Several explosions have occurred in the mines in recent years.

I hope to get more information. On page NIOSH there is good information.

Dear Kumari

You can see these articles:

and

The second article is in Bulgarian, but I think that you can send a message to the author in English.

Best regards.

USE  SOME  GIS APPLICATIONS 

Attached articles may be useful to you

I hope this attached paper may be useful.

Dr. Perumalla, you could consider using the flowing parametrs: the uniaxial compressive strength, tensile strength, and the thickness of the roof; the length and width of the extracted space of the longwall panel; the mining speed (i.e., the advance distance per day). 

D. Xuan

The typical methods of treatment for acidic and metal contaminated water effluent such as the Acid Mine Drainage (AMD) will always focus on either civil engineering methods, such as disposal, excavation, drainage and encapsulation or process based technologies such as effluent washing and treatment. These techniques are not environmental friendly, costly and unsustainable, thus environmental damaging. Nowadays, there is a growing need for an alternative remediation treatment that is innovative and more natural in order to prevent pollution in the environment. Therefore, in this study, a new alternative treatment, that is more organic, biodegradable and cost effective, using bone meal was presented. In this research, bone meal comprising of chicken bones were used as an alternative passive treatment to determine its potential in neutralizing and removing heavy metals from the abandoned cooper mine, Mamut Acid Mine Drainage (AMD) waste water effluent.

By using remote sensing, one can observe earth surface and its dynamic changes. If you know the surface change related to the underground coal mine fires (if possible, e.g. ground surface subsidence and temperature variation), then you can study on whether remote sensing is able to capture such phenomena. I think you can try SAR Interferometry (InSAR) for ground surface subsidence measurements and infrared remote sensing for temperature variation inversion. Good luck and best regards.

There are several methods of reclamation of mine waste lands. Physical, chemical and biological methods.  For ecological services physical followed by biological methods of re-vegetation seems to me to be perfect for clean up of environment. You can get several publications in context in my profile. If you get trouble to download please mail me at my mail id: rajcimfr@gmail.com. Best wishes.

Thankyou for your response Roland. I agree that the mining  companies and their associates have a duty of care and responsibility to mitigate such events from occurring. And it is concerning when a number of events have occurred in the past, which have been attributed to 'cutting corners', lack of appropriate monitoring and implementation of prevention mechanisms in place. It is particularly concerning when a $120 million river diversion project, (which won an award for engineering excellence in allowing further expansion of the mine) failed in 2012 when the river levee banks collapsed and caused the river to flood the mine. And with the effects of climate change, the wider region is projected to have more extreme rainfall events, longer periods of  heatwaves and fire-days in the future, which surely needs to bring greater attention and urgency to the matter.

The mines and the government are responsible for their own behaviour and decisions, the community has very little if no control of that. I suppose in terms what the community can do, is adapt to the changes themselves. They can only control, what they control. And that means minimising their energy use and being more efficient, producing their own energy on site with renewable energies such as solar power. But the community is struggling, socially, environmentally, and economically because of the power stations, and a shortly imposed, but recently scrapped carbon tax. Steps are in place to try convert the region into a low-carbon economy, however the fallout in the transition process has failed to adequately allow for job losses and accommodate for the production of more jobs.

During roof deterioration, numerous small and big cracks form in the roof. Every crack formation causes electromagnetic radiation. Therefore, with cumulative record of the electromagnetic radiation, on can get an estimate of the magnitude of roof deterioration.

I think we can minimize and also it is possible to have zero accidents in the mining, using Instruments to control the stability and events in mining, real time monitoring.

Particulate matter (PM) in air includes a mixture of solids and liquid droplets. PM comes in a wide range of sizes - those less than 10 micrometers in diameter (PM10) are dangerous as those can get into the lungs with every breath we take and resulting in serious health problems. PM that are less than 2.5 micrometers (PM2.5) in diameter get generated in activities like combustion in power plants, residential forest fires and some industrial processes.

Control of PM emission - Indeed it is a big issue. There are guidelines to keep the PM in ambient air under control. Plantation over loose soils, sprinkling of water over haul roads and work areas, transportation of crushed minerals in covered vehicles (or over-head closed belt systems) etc. could be done.

Backfill is the best method for mining areas to prevent residue disposal. Back fill with construction materias waste or industrial waste materials. Another economic approach is carbonation of mining waste, residue and mine tailings

Also the incidence of occupational hazards among the workforce and may be pitching it against a low or normal risk occupation

The toxicity of produced water depends on a number of factors, among them:

--what's used to produce it (what's injected) and how

--the chemical profile of the coal

--the geology of the production area

--the size and flow of the body of water into which it's discharged

These are just a few. Produced water in offshore exploration is can be quite saline with higher mineral content, therefore heavier, than the surrounding water. It can contain solubility levels of the petrochemicals with which it's in contact. Consequently, its discharge can affect benthic biota.

Guess the answer would be that more information is needed before attempting to answer the question. Hope that helped,

K

We are employing Fixed and Variable cost analysis adjusted daily.

thanks David - this approved activity is in all of the water catchment areas for Sydney and prime agricultural land is not really secure either, if the water catchments were secure then the biodiversity would be much more secure - but we're pretty much in the same boat. the health literature is about as sparse as what you are describing. its quite astonishing. I certainly appreciate your response - altho the attachment didn't attach!