Blending & separating coal from diferernt seams.

[colly0410]

At Morogreen pit Waterloo seam coal came up a surface drift & Low main coal up the shaft & I presume it was processed separately in the screens for different markets. At Hucknall pit Deep Soft & Black Shale seams coal was mixed up underground. The BS coal discharged onto B's intake belt that carried Deep Soft B6's face coal that then discharged onto the main intake belt carrying Deep Soft A6's & A9's coal to the skip bunker. Deep Soft was a high quality coal & Black Shale not so high. I'm wondering if they could separate the 2 seams coal in the screens for different markets?

[John]

Once coal from different seams hit's the main trunk belt it's just coal. The only way of keep it separate is a different belt for each seam, hoist up a different shaft and process in a different washery.
I've no idea how they blended coal, but I recall at Clifton, North Wilford power station didn't like 100% Piper coal, burned too hot and damaged their boilers, grates???
When we were having roof problems on 43's Piper, the face had to be cut 24/7 to prevent it closing, management at Wilford were screaming blue murder, so one of the two faces in Tupton seam cut coal to blend with the Piper coal.
Tupton coal was crap, at least at Clifton. It's better known elsewhere as Low Main.
Again Wilford didn't like pure Tupton, I think it had a very high ash content, Brian might be able to correct me on that one. I also don't think it had a very high calorific value in relation to better seams.

[colly0410]

Heard that when Hucknall only mined Black Shale they had to blend it with other seams from other pits at Ratcliff on Soar power station. When I 1'st started at Hucknall they had 1 face in Main Bright, 3 in Deep Soft & 4 main road (east intake & return + north intake & return) headings + they were heading out K6's. Black Shale was almost floor to Roof coal with just a dirt band in the middle. They said some days the Black Shale heading coal output could almost equal the Deep Soft faces output..

[smshogun]

This is incorrect Colly, any power station coal was a blend of coal and hard dirt and the coal was only there to heat up the dirt as this burned much hotter than coal and was much more energy efficient to burn, and it used a lot less coal. Blackshale was mixed at an approximate ratio of 20% coal and 80 % dirt and this was adjusted slightly to get it "in grade" for the power stations requirements and needs, so lets explain this simply.

If you were a power station and you had an on stock capability of 3 months, this being the maximum amount of time the coal blend stood on the ground before use it was termed a lean blend as this may have 20% coal and 80 % dirt, but if power stations stockpiled coal reserves were much higher and the "on stock" capability was much higher such as 1 year they reduced the dirt in the blend and increased the coal to allow for natural deterioration of the coal so that it burned in exactly the same way that other fuels burned so they didn't have to adjust their boilers to accommodate different blends.

It didn't really matter which seam you used as you adjusted your blend to suit the coal and match it with the dirt to get the correct blend for a specific power station and its combustion requirements, similarly, when they tightened emissions from power stations the blend was adjusted again to reduce emissions, sulphur being the main one at the time of British Coal.

Steam coals were a different blend, they used pure lump coal with no dirt blended in with it and this was for open boiler types without forced induction such as use in steam engines or locomotives, as steam trains had a variable air input ratio which was dependent upon the travelling speed of the locomotive as the faster it went the more forced air induction it had, steam coals had the capability to still burn when the locomotive was stationary and standing such as when they were fired up and raising steam or waiting when coupling up when running freight, or standing in a station while picking up passengers. The basic requirement was to still produce sufficient heat to retain steam with no forced air.

One other variant of this was traction engine coal which people such as traction or steam engine enthusiasts such as Fred Dibner used as these had low speeds and little forced induction, and the coals used for both of these applications tended to be bright coals as they would burn with sufficient heat without any forced air induction.

Forging cokes were basically coal which had been coked and it was mixed with crushed limestone, it is more expensive as they have to buy the limestone, if you have access to a blacksmith who uses forging coke and he will let you take a shovel full and wash it with pure water you will see the limestone as when you wash it you will see the coke remain black and the limestone turn to a light grey or even an off white.   

[colly0410]

Thanks for info, might have confused the dirt blending with coal blending, was a long time ago since I worked down the pit & can't remember where I heard the blending story..

[dazbt]

Colly, read the attached report and make your own mind up, coal fired power stations are designed or, even altered and adapted to suit variations in 'available coal', blending of different coals is often essential to maintain optimum efficiency. I'm certainly no expert nor do I pretend to be but, the only time I've heard of adding dirt in the 'massive 'proportions stated is with fluidised bed systems. Read this for what I perhaps in ignorance believe to be closer the proper facts;

pdfs.semanticscholar.org/a7f7/39b7a19d76566399224928ef701f54fd1977.pdf

[smshogun]

Interesting report Daz, but look at the date of the report? then look at the factual basis of the report as it clearly states it is a hypothesis based upon other reports and in no way factual as an absolute, just an opinion using other reports as substantiation to give it some form of credibility. This report is based solely upon today and not on the NCB/British Coal era when we had collieries in which we worked.

Blending of different coals has always gone on and it goes right back to the beginnings of time when coal mining occurred and latterly in coal mining history when coal was the only real source of electricity production as many power stations used multiple collieries as sources of coal for security of coal supplies and guaranteed supplies to keep the electricity grid alive, and this is why the NCB/British Coal had a grading system designed around colliery production of specific types or grades of coal, that would guarantee that any coal blends bought from any colliery within the NCB or British Coal would be of a guaranteed grade and this was under a formalised contract, and any contract has benefits and liabilities.

Around the late 1980's the Scottish electricity generators began importing coal for power production solely because it was cheaper, suddenly they were hit by the liabilities, they had specified a grade or standard of coal to be supplied and this was spot bought and they saved a fortune in buying it, suddenly the liabilities hit them hard as they were burning out the grates "en masse" when they used the imported coal and they had no formalised liability clauses as they did with British Coal which were that if a colliery supplied an out of grade blend, then British Coal picked up the cost and the generators had no financial loss, and the cost of replacing a single grate cost them around £1M a pop and they were suddenly £millions out of pocket by trying to save some money on buying coal cheaply, then being hit with the cost of replacing a huge amount of grates and losing sales from the lost production.   

[dazbt]

OK as I said I'm no expert, I bow to your much greater knowledge ................................ but,                                                                                                                 80% DIRT ?

[smshogun]

Yes 80% dirt and not just ordinary dirt, they used the rocks mined from underground as this was suitable for the blends the power stations demanded and it was a cheap, waste material.

Some power stations in various parts of the world use much less dirt in their blends and some even use pure coal; but hey, that's life.

[dazbt]

Mar 3, 2018 11:12:41 GMT -5 smshogun said:

Interesting report Daz, but look at the date of the report? then look at the factual basis of the report as it clearly states it is a hypothesis based upon other reports and in no way factual as an absolute, just an opinion using other reports as substantiation to give it some form of credibility. This report is based solely upon today and not on the NCB/British Coal era when we had collieries in which we worked.

Blending of different coals has always gone on and it goes right back to the beginnings of time when coal mining occurred and latterly in coal mining history when coal was the only real source of electricity production as many power stations used multiple collieries as sources of coal for security of coal supplies and guaranteed supplies to keep the electricity grid alive, and this is why the NCB/British Coal had a grading system designed around colliery production of specific types or grades of coal, that would guarantee that any coal blends bought from any colliery within the NCB or British Coal would be of a guaranteed grade and this was under a formalised contract, and any contract has benefits and liabilities.

Around the late 1980's the Scottish electricity generators began importing coal for power production solely because it was cheaper, suddenly they were hit by the liabilities, they had specified a grade or standard of coal to be supplied and this was spot bought and they saved a fortune in buying it, suddenly the liabilities hit them hard as they were burning out the grates "en masse" when they used the imported coal and they had no formalised liability clauses as they did with British Coal which were that if a colliery supplied an out of grade blend, then British Coal picked up the cost and the generators had no financial loss, and the cost of replacing a single grate cost them around £1M a pop and they were suddenly £millions out of pocket by trying to save some money on buying coal cheaply, then being hit with the cost of replacing a huge amount of grates and losing sales from the lost production.   

smshogun Will you give me permission to copy this post and share it ?

[dazbt]

Feb 27, 2018 21:05:34 GMT -5 smshogun said:

This is incorrect Colly, any power station coal was a blend of coal and hard dirt and the coal was only there to heat up the dirt as this burned much hotter than coal and was much more energy efficient to burn, and it used a lot less coal. Blackshale was mixed at an approximate ratio of 20% coal and 80 % dirt and this was adjusted slightly to get it "in grade" for the power stations requirements and needs, so lets explain this simply.

If you were a power station and you had an on stock capability of 3 months, this being the maximum amount of time the coal blend stood on the ground before use it was termed a lean blend as this may have 20% coal and 80 % dirt, but if power stations stockpiled coal reserves were much higher and the "on stock" capability was much higher such as 1 year they reduced the dirt in the blend and increased the coal to allow for natural deterioration of the coal so that it burned in exactly the same way that other fuels burned so they didn't have to adjust their boilers to accommodate different blends.

It didn't really matter which seam you used as you adjusted your blend to suit the coal and match it with the dirt to get the correct blend for a specific power station and its combustion requirements, similarly, when they tightened emissions from power stations the blend was adjusted again to reduce emissions, sulphur being the main one at the time of British Coal.

Steam coals were a different blend, they used pure lump coal with no dirt blended in with it and this was for open boiler types without forced induction such as use in steam engines or locomotives, as steam trains had a variable air input ratio which was dependent upon the travelling speed of the locomotive as the faster it went the more forced air induction it had, steam coals had the capability to still burn when the locomotive was stationary and standing such as when they were fired up and raising steam or waiting when coupling up when running freight, or standing in a station while picking up passengers. The basic requirement was to still produce sufficient heat to retain steam with no forced air.

One other variant of this was traction engine coal which people such as traction or steam engine enthusiasts such as Fred Dibner used as these had low speeds and little forced induction, and the coals used for both of these applications tended to be bright coals as they would burn with sufficient heat without any forced air induction.

Forging cokes were basically coal which had been coked and it was mixed with crushed limestone, it is more expensive as they have to buy the limestone, if you have access to a blacksmith who uses forging coke and he will let you take a shovel full and wash it with pure water you will see the limestone as when you wash it you will see the coke remain black and the limestone turn to a light grey or even an off white.   

smshogun and would you give me permission to share this as well please

[dazbt]

Feb 27, 2018 21:05:34 GMT -5 smshogun said:

This is incorrect Colly, any power station coal was a blend of coal and hard dirt and the coal was only there to heat up the dirt as this burned much hotter than coal and was much more energy efficient to burn, and it used a lot less coal. Blackshale was mixed at an approximate ratio of 20% coal and 80 % dirt and this was adjusted slightly to get it "in grade" for the power stations requirements and needs, so lets explain this simply.

If you were a power station and you had an on stock capability of 3 months, this being the maximum amount of time the coal blend stood on the ground before use it was termed a lean blend as this may have 20% coal and 80 % dirt, but if power stations stockpiled coal reserves were much higher and the "on stock" capability was much higher such as 1 year they reduced the dirt in the blend and increased the coal to allow for natural deterioration of the coal so that it burned in exactly the same way that other fuels burned so they didn't have to adjust their boilers to accommodate different blends.

It didn't really matter which seam you used as you adjusted your blend to suit the coal and match it with the dirt to get the correct blend for a specific power station and its combustion requirements, similarly, when they tightened emissions from power stations the blend was adjusted again to reduce emissions, sulphur being the main one at the time of British Coal.

Steam coals were a different blend, they used pure lump coal with no dirt blended in with it and this was for open boiler types without forced induction such as use in steam engines or locomotives, as steam trains had a variable air input ratio which was dependent upon the travelling speed of the locomotive as the faster it went the more forced air induction it had, steam coals had the capability to still burn when the locomotive was stationary and standing such as when they were fired up and raising steam or waiting when coupling up when running freight, or standing in a station while picking up passengers. The basic requirement was to still produce sufficient heat to retain steam with no forced air.

One other variant of this was traction engine coal which people such as traction or steam engine enthusiasts such as Fred Dibner used as these had low speeds and little forced induction, and the coals used for both of these applications tended to be bright coals as they would burn with sufficient heat without any forced air induction.

Forging cokes were basically coal which had been coked and it was mixed with crushed limestone, it is more expensive as they have to buy the limestone, if you have access to a blacksmith who uses forging coke and he will let you take a shovel full and wash it with pure water you will see the limestone as when you wash it you will see the coke remain black and the limestone turn to a light grey or even an off white.   

Figures for 2017 UK Power Stations coal usage is 8,720,000 tonnes which 'obviously' then means that 34,880,000 tonnes of dirt was used, if the above is to be believed, that's a lot of muck.

[smshogun]

It also assumes that all boilers are the same when they are not as some boilers used are/were pure coal burners while others had the capability to use pure wood.

[erichall]

During the 70's and 80's, whilst working there, High moor mined the 'Two Foot' seam, above the Clowne seam, and all thr product, including Development and Ripping dirt was sent out of the pit as a run-of-mine product. This was 'sweetened' by the addition of washed slurry from different collieries, some of which included coal from the North East. All coal of +2" was sent to Warsop washery for sale a washed large coal. The larger proportion, with an ash content of 8-15%, I believe, was sent by road to the power stations in the West Burton Area. The % was checked periodically, and the only time we had complaints from the Generating Stations was if the % was too high.

[smshogun]

That would be correct Eric, they used different blends for the requirements of the power stations they supplied, if they supplied different markets such as Moorgreen did they did different blends in the CPP, they produced singles, doubles, trebles, steam lumps and power station coal and the washed and sized coal would be left "as is" for the domestic coal, the power station coal was mixed with dirt and slurry and dried out before going straight into coal wagons under the CPP or across onto the flagpole belt and dropped onto the ground for loading into lorries for private boilers used in industry at local companies.

Do you remember the picking table? do you remember Lucky Seven? all the lump coal was sent to the picking table and as it rotated it was raked across by hand by lucky 7 so the discharge plates could scoop it off into hoppers; at that time it was 4-8" and 7-12" and 12" and above.