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Been good news for the Green`s this month
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vegplot



Joined: 19 Apr 2007
Posts: 21298
Location: Ynys Môn
PostPosted: Thu Jul 02, 15 3:42 pm    Post subject:  Reply with quote    

Cement production relies heavily on coal both as a fuel (burns hotter than gas and with greater luminosity) and also because cement products often use flyash from coal powered power stations. Other fuels are used and as Slim points out even tyres are burned. Cement is certainly not an environmentally sound product.

I'm happy to say our new build home won't be using any cement at all.

dpack



Joined: 02 Jul 2005
Posts: 35527
Location: yes
PostPosted: Thu Jul 02, 15 3:46 pm    Post subject: Reply with quote    

cement using tyres could be a good idea so long as the scrubbers work but as a simple long,hot,turning tube with no environmental controls it would be very messy

Ty Gwyn



Joined: 22 Sep 2010
Posts: 4260
Location: Lampeter
PostPosted: Thu Jul 02, 15 4:45 pm    Post subject: Reply with quote    

The best grades of coking coal in the UK were only obtained in Durham and South Wales.

A meeting i attended in Cardiff Uni,Mining engineers regarding the Margam drift mine proposal by Tata in Port talbot,a few year`s back,the coal used there came from a large opencast in Mozambique.

Up to date all cement works in the UK use coal in the production,

And as far as i know,all Hot Lime is produced with coal as well,not heard of any other fuel used.

Falstaff



Joined: 27 May 2009
Posts: 1014

PostPosted: Thu Jul 02, 15 9:29 pm    Post subject: Reply with quote    

Just out of curiosity, producing 1 tonne of cement, releases 1.6 tonnes of CO2 from the limestone !

- Irrespective afaik of whether the heating is done by burning imported gas - or good old midlands coal !

vegplot



Joined: 19 Apr 2007
Posts: 21298
Location: Ynys Môn
PostPosted: Thu Jul 02, 15 9:47 pm    Post subject: Reply with quote    

Ty Gwyn wrote:
The best grades of coking coal in the UK were only obtained in Durham and South Wales.

A meeting i attended in Cardiff Uni,Mining engineers regarding the Margam drift mine proposal by Tata in Port talbot,a few year`s back,the coal used there came from a large opencast in Mozambique.

Up to date all cement works in the UK use coal in the production,

And as far as i know,all Hot Lime is produced with coal as well,not heard of any other fuel used.


I don't have any figures but this suggests that not all cement production uses coal as the fuel source...
Quote:
Alternative fuels have been successfully used in cement kilns for decades. In the UK, alternative fuels used include secondary liquid fuels, scrap tyres, paper, packaging and household waste, meat and bone meal and sewage sludge pellets.

Falstaff



Joined: 27 May 2009
Posts: 1014

PostPosted: Thu Jul 02, 15 9:52 pm    Post subject: Reply with quote    

vegplot wrote:


I don't have any figures but this suggests that not all cement production uses coal as the fuel source...
Quote:
Alternative fuels have been successfully used in cement kilns for decades. In the UK, alternative fuels used include secondary liquid fuels, scrap tyres, paper, packaging and household waste, meat and bone meal and sewage sludge pellets.


I'm not at all sure that burning old tyres is better than burning coal, but it would at least be useful to know where the "Quote" - comes from ?

Ty Gwyn



Joined: 22 Sep 2010
Posts: 4260
Location: Lampeter
PostPosted: Thu Jul 02, 15 10:28 pm    Post subject: Reply with quote    

Just had a look up regarding lime production,and the fuel source is much the same as Veg stated for cement,which shocked me,as years back when we had a load of hot lime from Llandybie lime firms,one would always find lump`s of coal through it,

I was also shocked by the C02 produced in the process of calcinating,if Falstaffs figures are correct regarding the amount of CO2 produced what ever fuel is used in the process,considering the amount of lime used,it is as bad if not worse than coal in this CO2 adding to the atmosphere.

Tavascarow



Joined: 06 Aug 2006
Posts: 8407
Location: South Cornwall
PostPosted: Thu Jul 02, 15 10:38 pm    Post subject: Reply with quote    

Ty Gwyn wrote:
Just had a look up regarding lime production,and the fuel source is much the same as Veg stated for cement,which shocked me,as years back when we had a load of hot lime from Llandybie lime firms,one would always find lump`s of coal through it,

I was also shocked by the C02 produced in the process of calcinating,if Falstaffs figures are correct regarding the amount of CO2 produced what ever fuel is used in the process,considering the amount of lime used,it is as bad if not worse than coal in this CO2 adding to the atmosphere.
AFAIA lime does use as much energy in its production as cement but unlike cement lime reabsorbs carbon from the atmosphere as it slowly cures so in time becomes carbon neutral. Vegplot will no doubt be along to put it in a more technical format.

Ty Gwyn



Joined: 22 Sep 2010
Posts: 4260
Location: Lampeter
PostPosted: Thu Jul 02, 15 10:48 pm    Post subject: Reply with quote    

That is interesting if true,as i was about to ask if Cement and Lime pay the same 20% carbon tax as coal in the UK,as against the 5% in the EU

dpack



Joined: 02 Jul 2005
Posts: 35527
Location: yes
PostPosted: Thu Jul 02, 15 11:14 pm    Post subject: Reply with quote    

the same amount of co2 released from limestone when making cement or lime is reabsorbed from (dissolved)atmospheric co2 as the mortar cures

cement and lime cure back to carbonates therefore only the co2 from the fuel is added to the global carbon dioxide count unless the fuel is plant based such as tyres which grow on trees now rather than from trees/bugs held as fossils:lol:

charcoal fueled lime or cement would be carbon neutral so long as coppice or replanting was done

Falstaff



Joined: 27 May 2009
Posts: 1014

PostPosted: Thu Jul 02, 15 11:47 pm    Post subject: Reply with quote    

dpack wrote:
the same amount of co2 released from limestone when making cement or lime is reabsorbed from (dissolved)atmospheric co2 as the mortar cures

cement and lime cure back to carbonates therefore only the co2 from the fuel is added to the global carbon dioxide count unless the fuel is plant based such as tyres which grow on trees now rather than from trees/bugs held as fossils:lol:

charcoal fueled lime or cement would be carbon neutral so long as coppice or replanting was done


What a load of old bollix

Tavascarow



Joined: 06 Aug 2006
Posts: 8407
Location: South Cornwall
PostPosted: Fri Jul 03, 15 6:19 am    Post subject: Reply with quote    

dpack wrote:
the same amount of co2 released from limestone when making cement or lime is reabsorbed from (dissolved)atmospheric co2 as the mortar cures

cement and lime cure back to carbonates therefore only the co2 from the fuel is added to the global carbon dioxide count unless the fuel is plant based such as tyres which grow on trees now rather than from trees/bugs held as fossils:lol:

charcoal fueled lime or cement would be carbon neutral so long as coppice or replanting was done

AFAIA cement reacts with water not atmospheric CO2 & cure rapidly because of this, traditional lime mortars cure slowly & return to carbonate through reaction to atmospheric CO2.

Mistress Rose



Joined: 21 Jul 2011
Posts: 10898

PostPosted: Fri Jul 03, 15 6:37 am    Post subject: Reply with quote    

Traditionally, coppice was used to make charcoal for iron production. In fact we are going to the site of a 17th century iron works on Saturday, and the coppice is still there.

If charcoal is used for either limestone burning or iron smelting, it will be more carbon neutral if it is locally produced, but would need an awful lot of coppice for modern industrial quantities, and will need some fossil fuel input for cutting. Sadly, it would probably be imported, but at least is less likely to import pests and diseases than other imported biomass.

Falstaff



Joined: 27 May 2009
Posts: 1014

PostPosted: Fri Jul 03, 15 7:39 pm    Post subject: Reply with quote    

Tavascarow wrote:
dpack wrote:
the same amount of co2 released from limestone when making cement or lime is reabsorbed from (dissolved)atmospheric co2 as the mortar cures

cement and lime cure back to carbonates therefore only the co2 from the fuel is added to the global carbon dioxide count unless the fuel is plant based such as tyres which grow on trees now rather than from trees/bugs held as fossils:lol:

charcoal fueled lime or cement would be carbon neutral so long as coppice or replanting was done

AFAIA cement reacts with water not atmospheric CO2 & cure rapidly because of this, traditional lime mortars cure slowly & return to carbonate through reaction to atmospheric CO2.


Cement sets by a process of crystallisation.

As lime mortar sets, it develops a holdand slowly (VERY slowly) the lime does combine with acidic carbon, to return to a calcium carbonate state.

I believe some of the Roman stuff has got part way down the path already !

If that is regarded as "Carbon neutral" by the Greenies, it would not surprise me at all in this crazy subject !

Mistress Rose



Joined: 21 Jul 2011
Posts: 10898

PostPosted: Sat Jul 04, 15 7:48 am    Post subject: Reply with quote    

I think that lime mortar has a lot of other advantages, particularly in old buildings, over cement. On the other hand, cement will set under water, so whichever suits which purpose. Lime mortar can also be reused if rebaked, whereas cement has to be just broken down and used as hardcore.

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