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James Cockshutt Esq, Huthwaite Nov 14 1806
Along with this I have sent you an Acct of the operation of Roasting the Lead Ore previous to its being smelted according to your direction as exact as it could possibly be made, as I attended to the weighings necessary at the different works myself which were performed with the utmost scrupulous exactness. –
Yet you will observe that the results are very different at each place – I have attempted to account for the difference between the results of Allenheads and Rookhope Mills in the manner that struck me as the most likely at the time – and which I submit to your consideration and I rather think from the manner in which I understand the roasting was conducted at Dukesfd the same reasoning will equally apply there. – The difference arising from the roasting at Allendheads compared with that of Rookhope Dukesfd may in great measure be accounted for from the different kinds of Lead Ore, as there is little doubt that the benefit will vary in the Ore of different Mines independent of its quality as well as the degree of roasting it has undergone
altho the benefit of roasting the ore appears less at Dukesfd than Rookhope Mill yet the general benefit at Dukesfd exceeds that at Rookhope as you will observe that the quantity of lead made at Dukesfield in both the operations is greater than at Rookhope from the same quantity of Ore of the same quality as they were both from the same heap at the mine, the Agent there having particular directions to that effect.
You will observe from the papers that the roasted Ore requires less fuel to smelt it for the full quantity smelted but requires more fuel during the time the Hearth is at work as the Lead runs considerably quicker and sooner heats the Hearth which has made some people imagine that it may injure its quality but I cannot say that I observe any difference, but we will be better able to determine that afterwards as I had a particular mark set upon the Lead made at each Mill to distinguish the Roasted from the unroasted Ore Lead, and when we receive it at Blaydon we intend to refine it there and get it made into Whitelead and if it should answer that purpose there is little doubt but it maybe used for any thing that Lead is applied to.
The above are all the observations I have at present to make. I hope they will answer the purpose intended. As I assure you that every attention was given by the Agents at the different works as well as by myself in order that the greatest degree of accuracy might be obtained
I am J Mulcaster
Dukesfield Smelt Mill 1 Nov 1806
Taken 30 Bings of Breckonsike Bouse Ore and worked it at the Ore Hearth in the ordinary Way
Produced at c q lb hours fothers
Ore Hearth 112 ps Lead Wt 154 - 24 worked 53 1/2 used 6/7 coals
Slag Hearth 3 1/2 ps 4 3 8 7 3/4 1 cinders
In all 115 1/2 Ps Lead Wt 159 - 4 worked 61 1/4 used 1 6/7 Frs
NB. The grey Slags made at the Ore Hearth from the above Ore weighed previous to being smelted in the Slag hearth 30c[wt] –q -lb
Taken 30 Bings more of Breckonsike Bouse Ore exactly of the same quality as the preceding --the Ore being weight from the same heap to the Ore Hearth and the Roasting Furnace alternately 1/8 of a Bing at each weight.
The Roasting Furnace required 59 ¼ hours to roast the Ore, In which time 2 4/7 Frs of coals were consumed in that operation. The Ore after roasting had lost 6c –q -lb of its original weight. It was then taken to the Ore hearth and smelted in the same manner as the preceding and produced as below.
Produced at c q lb hours fothers
Ore Hearth 117 Ps lead Wt 161 1 14 worked 46 used 11/14 Coals
Slag Hearth 3 1/2 4 3 22 6 1/2 12/14 Cinders
Roasted Ore 120 1/2 Ps Ld 166 1 8 worked 52 1/2 1 9/14 Fothers
Unroasted 115 1/2 159 0 4 61 1/4 1 12/14
More Lead
by Roasts 5 pieces 7 1 4
More time & fuel by unroasted 8 3/4 hours 3/14 Fothers
NB The grey slags made from the roasted ore weighed previously to be smelted at the Slag Hearth 33c 3q 0lb
c q lb c q lb
Roasted Ore made common Lead 161 1 14 Slag Lead 4 3 22
Unroasted ore &c 154 – 24 4 3 8
Difference 7 – 18 14
Expenses incurred by Roasting & Smelting 30 Bings of Lead Ore
Roasting 30 Bings of Lead Ore @ 1/6 2 5 0
Coals consumed for do 2 4/7 Fo @ 6/6 16 8 1/2 3 1 8 1/2
Smelters Wages for 7 tons 5 p Lead @ 7/4 2 13 7 1/2
Weighing Ore for 7 8 @ 4d 2 6
Do Lead for 7 8 @ 3 1/2d 2 2 1/4
Getting in Peats 7 8 @ 2 d 1 3
Peats consumed ----5 1/2 Sacks @ 9d 4 1 1/2
Coals -do - 11/14 Fothers @ 6/6 5 1 1/4 3 8 9 1/2
Slag hearth Smelter Wages
for 4c 3q 22 lb lead @16/- 3 7 1/2
Cinders assumed for do 6/7 Fo @ 8/- 6 10 1/2 10 6
Total Charge of Roasting Smelting 30 Bings of Ore £7 1 0
Expenses incurred by smelting (common way) 30 Bings of Lead Ore
Smelters Wages for 7 tons of lead @ 7/4 2 11 8
Weigh Ore & Lead for 7 do &3 ps do 7 1/2 4 6
Getting in Peats for 7 3 2 1 2 1/2
Peats consumed 7 sacks @ 9d 5 3
Coals do 6/7 Fos @ 6/6 5 7 3 8 2
Slag Hearth Smelters Wages
for 4c 3q 8lb lead @16/- 3 6
Cinders consumed for do 1 Fo @ 8/- 8 0 11 6
Total charge of smelting 30 Bings Ore (Common way) £3 19 8 1/2
Extra expense occasioned by roasting 3 bings ore £3 1 3 1/2
More lead obtained by roasting 7c 1q 4lb @ £36-3–3 pr F £12 10 10 3/4
Deductg the expense of Carr: to Blaydon 16–9
Extra expense occasioned by roasting as above 3 1 3 1/2
Net profit remaining in <favour> of roasting the Ore 9 9 7 1/4
The above Profit is = 6/3 3/4 per Bing of Ore or £1–4-11 1/2 per Fr of lead
Observations
The roasting the 30 Bings Lead Ore for this experiment was performed Bing after Bing untill the whole was completed as done at Rookhope Mill the Furnace being continued working from the beginning to the end of the Operation – As I was not present during the time of roasting I could
not make any observations of the comparative heat used here with Allenheads & Rookhope Mills. The average time required to roast each Bing of the Ore was 1.975 hours, the Coals consumed 0.0805 Fo[the]rs and the loss of weight 0.26 cwts for each bing of Ore or 2.5 p Cent.
Previous to smelting both the roasted and unroasted Ore the Lead <laid> out of the Pan of the Hearth with the Brouse necessary to begin smelting with were weighed as well before as after each operation, the same as at Allenheads & Rookhope Mills so that by this means the exact quantity of Lead obtained from the Unroasted and Roasted Ore was ascertained.
The average & comparative time as well as the consumption of fuel in each operation was as below
Unroasted ore 1.783 hours 0.0285 Fos of Coals required for each Bing of ore
Roasted 1.533 0.0262 for each Bing
do 0.0170 Fos of Coals for each hour of working
Unroasted 0.0159 for each hour
J Mulcaster
Rookhope Smelt Mill 18th October 1806
Experiment of Roasting Lead Ore
Taken 30 Bings of Breckonsike bouse ore and worked it at the Ore Hearth in the ordinary way which produced as below
at the c q lb Loads
Ore Hearth 105ps of lead q 145 3 - worked 62 1/2 hours used 7 Coals
Slag Hearth 3 3 3 19 10 7 Cinders
In all 108 Cwt 149 2 19 72 1/2 14 loads
NB the grey slags made at the Ore Hearth from the above Ore weighed before being smelted at the Slag Hearth Cwt 32 – 2-0
Taken 30 Bings more of Breckonsike Ore exactly of the same quality as the above – the Ore being weighed from the same heap to the Ore Hearth, and to the roasting furnace alternately 1/8 of a Bing at each weigh – the Roasting furnace required 59 hours to roast the above Ore in which time 14 Loads of Coals were consumed. - The Ore by roasting had lost 7c 2st 4lb of its original weight – it was then taken to the Ore Hearth and Smelted in the same manner as the
preceding which produced as below
Ore hearth 113 ps lead 155-1-20 worked 45 3/4 hours used 6 1/2 coals
Slag hearth 3 4 2 7 3/4 6 cinders
Roasted 116 159 1 22 53 1/2 12 1/2
Unroasted 108 149 2 19 72 1/2 14
More lead
By roasting 8 9 3 3
More time & fuel by the unroasted 19 hours 1 1/2 loads
NB the grey slags made at the Ore Hearth from the roasted Ore weighed before being smelted at the Slag Hearth 30c 2q 0lb
c q lb c q lb
Roasted ore made from Lead 155 1 20 Slag lead 1 - 2
Unroasted do 145 3 - do 3 3 19
Difference 9 2 20 - - 11
Expenses incurred by roasting and smelting 30 Bings of Lead Ore
Roasting Ore for 7 Tons 1 p lead @5/4 1 17 8
Coals consumed 14 loads @1/6 1 1 - 2 18 8
Smelting wages for 7 tn & 1 p @7/4 2 11 9 1/2
Weighing Ore for 7 4 @4 2 5
Weighing Lead for 7 4 @4 2 5
Peats consumed for 7 tons 4 ps @1/4 9 8
Coals do 6 1/2 loads @1/6 9 9 3 16 1/2
Slag Hearth Smelting Wages 3 ps @16/- 3
Cinders consumed for do 6 loads @1/4 8 11
Total charge of Roasting and
smelting 30 Bings of Lead ore £7 5 8 1/2
Expenses incurred by Smelting (Common Way) 30 Bings of Lead Ore
Smelters wages for 6 Tons 9ps @7/4 2 8 1 1/2
Weighing Ore and Lead for 6–12 @8 4 6
Peats consumed for 6–12 @1/4 9 -
Coals 7 loads @1/6 10 6 3 12 1 1/2
Slag Hearth Smelting Wages 3 ps @16/- 3
Cinders consumed - 7 Loads @1/4 9 4 12 4
Total charge of smelting 30 ps lead (Common way) £4 4 5 1/2
Extra expense occasioned by roasting 30 Bings ore £3 1 3
C q lb
More Lead obtained by roasting 9 3 3 @ £35 17 6 pr Fo
allowing for expense Carrge to Blaydon 1 2 6 16 13 11 1/2
Extra expense occasioned by roasting as above 3 1 3
Neat profit remaining in favor of roasting the ore £13 12 8 1/2
The above profit is 9/1 per Bing of Ore or £1 -18-2 1 ½ per Fo[the]r of lead. The ore and lead carriage will be £13-4-0 so that the above Saving will more than repay that expense
Observations
The roasting of the Lead Ore at this Mill was performed bing after bing untill the whole was completed the furnace being continued working from the beginning to the end of that operation. The Ore was subjected to a greater degree of heat here than at Allenheads Mill, the temperature of the furnace being kept higher as well as being exposed a longer time to its influence – the furnace at this place is considerably smaller and more powerful than that at Allenheads.
The Average time required to roast each bing of the Ore was 1.966 hours the Coals consumed 0.466 loads and the loss of weight by roasting 0.254 Cwts to each bing of ore or 3.177 per Cwt but probably was more, as the Ore after being roasted lay at the Door all night, before being weighed, and a considerable quantity of rain having fallen during that time it would of course absorb a little water and consequently increase its weight & therefore make the diminution of its original weight appear less that it really was – Previous to smelting both the unroasted and roasted Ore the Lead in the pan of the Hearth with the Brouse were weighed as well before as after each operation the same as done at Allenheads Mill by which means the exact quantity of Lead obtained from the unroasted & roasted Ore were calculated. – The average time consumption of fuel was as follows
Unroasted ore 2.083 hours 0.0233 Loads of Coals for each Bing of ore
Roasted 1.5025 0.0216 for each Bing
Unroasted 0.112 loads Coals for each hour of working
Roasted 0.142 for each hour
Mem: the benefit arising from the Roasting the Lead Ore previous to its being smelted appearing so very different at Allenheads & Rookhope Mill I think may arise from the Ore being exposed to a stronger heat at Rookhope Mill, and consequently more of the Sulphur evaporated, and probably the loss of the Lead in the operation of smelting may be in the inverse ratio the Sulphur bears to the metallic part of the Ore J Mulcaster
Allenheads Mill 11th Octr 1806
Experiment of Roasting Lead Ore
Taken 25 Bings of Allenheads Bouse Ore and worked it at the Ore Hearth in the ordinary way which produced as below.
c q lb Loads
Ore Hearth 131ps of lead q 130 3 - worked 67 hours used 8 1/2 Coals
Slag Hearth 2 2 1 23 5 1/2 3 1/2 Cinders
In all 133 Cwt 133 - 23 72 1/2 12 loads
NB the grey slags made at the Ore Hearth from the above Ore weighed before being Smelted at the Slag Hearth 22 – 3- 7
Taken 25 Bings more of Allenheads bouse Ore exactly of the same quality as the above – the Ore being weighed from the same heap to the Ore hearth, and to the Roasting furnace alternately ¼ Bing, at each weigh. – The Roasting furnace required 45 ¾ hours to roast the above Ore in which time 13 loads of Coals were consumed. The Ore after roasting was diminished c s lb 6 - 7 of its original weight. – it was then taken to the smelting hearths and produced -
Ore hearth 131 ps lead 133 - 14 worked 49 1/2 hours used 6 1/2 coals
Slag hearth 2 1/2 3 2 7 1/2 3 1/2 cinders
Roasted 133 1/2 136 - 16 57 10
Unroasted 133 133 - 23 72 1/2 12
More lead
By roasting 1/2 2 3 25
More time & fuel by the unroasted 15 1/2 2 loads
NB the grey slags made at the Ore Hearth from the roasted Ore weighed previous to smelting at the slag hearth 23 – 3 – 0
c q lb c q lb
Roasted ore produced common Lead 133 - 14 Slag lead 3 - 2
Unroasted do 130 3 - 2 1 23
Difference common lead 2 1 14 Slag - 2 7
Expenses incurred by roasting & smelting 25 Bings Lead Ore
Roasting 25 bings lead ore @1/6 1 17 6
Coals consumed 13 loads @1/6 19 6 2 17 -
Weighing Ore to furnace for 6 tn @3 1 6
Smelting wages for 5 21 p @7/4 2 3 8
Weighing Lead for 6 @4 2 -
Peats consumed for 6 @1/10 11 -
Coals do 6 1/2 loads @1/6 9 9 3 7 11
Slag Hearth Smelting Wages 2 1/2p@16/- 2 2
Cinders consumed 3 1/2 loads @1/6 5 3 7 5
Total charge of Roasting and
smelting 30 Bings of Lead ore £6 12 4
Expenses incurred by smelting 25 Bings of Ore (Common way)
Smelters wages for 5 Tons 21ps @7/4 2 3 8
Weighing Ore and Lead for 6 tons @7 3 6
Peats consumed for 6 @1/10 11 -
Coals 8 1/2 loads @1/6 12 9 3 10 11
Slag Hearth Smelting Wages 2 ps @16/- 1 9
Cinders consumed – 3 1/2 Loads @1/6 5 3 7 -
Full expense of smelting 25 ps lead (Common way) £3 17 11
Extra expense occasioned by roasting 25 Bings ore £2 14 5
C q lb
More Lead obtained by roasting 2 3 21 @ £35 15
Deducting the expense Carr to Blaydon 1 5 5 - -
Extra expense occasioned by roasting as above 2 14 5
Neat profit remaining in favor of roasting the ore £2 5 7
The above profit is 1/9 ¾ per Bing of Ore or £~ 7 2 ½ per pig of lead
Observations
The Roasting of the 25 Bings of Lead Ore at the Mill was performed at 2 shifts or changes of work a sufficient quantity of ore not being at the Mill (belonging the tryal) to keep the furnace at work the whole time of the operation so that the consumption of Coals would be a little increased but could not exceed ½ load as it was only 3 ½ hours between the finishing of the first, and the beginning of the second shift. The average time required to roast each bing of the Ore was 1.83 hours. The Coals consumed 0.52 loads & the loss of weight 0.2423 Cwts to each Bing of Ore or 3.003 per Cwt
Previous to the experiment being commenced The old brouse was laid aside, and the lead ore laid out of the pan of the Hearth, and their weight ascertained, as it was necessary to make use of them at the beginning of the 1st shift of smelting. At the end of each of the operations of smelting the unroasted as well as the Roasted Ore the weighing of the Lead left in the hearth with the Brouse remaining always after each operation was again repeated as above, by which method the exact quantity of Lead, obtained in each of the operations was ascertained. The average time and consumption of fuel occasioned by Smelting at the Ore Hearth each of the <…….> was as below.
Unroasted Ore 2.68 hours 0.34 loads of Coals for each Bing of Ore
Roasted -do- 1.98 0.26 for each Bing
-do- 0.131 loads of Coals for each hour of working
Unroasted 0.126 for each hour
J. Mulcaster
