Note: Descriptions are shown in the official language in which they were submitted.
53~$
Thi q invention relate~ to the smeltin~ o~
non-ferrous metal~ and, more particularly, to a method
of operating converter furnaces for treating the matte
produced in ~melting furnace ~uch a-~ bla~t ~urnace and
flash ~meltin~ furnace.
Or~ obtained f~om mine~ are treated to obt~ined
concentrate~ containing more ~aluable metals by mean~
of the flotation proces~, and such concentrate~ ara
refined to final metal product in the ~melter.
The ¢opper or nickel ~ulfide concentrate i~
treated in a ~melting furnace to produce matt~, which
i~ further treated in converter furnaces to obtain,
in ca~e of copper ~mel*in$, the blister copper, while
the S02 ga~ prod~ced in the smelting furnace and
o~nverter fu~ace i9 recovered a~ ~ulfuric acid.
Usually, the matte produced in the ~melting furnace
i~ ohar$ed into converter furnace~ in~talled at near the
~melting furnace in mvlten state, altho~gh in ~ome ca~e~
it i~ tranaported into remote converter~ or other ~melter.
In the f~rmer ca~e, it i~ of cour~e most
effective and ~conomical frsm the ~tand point of the
economy of in~e~tment that the con~erter ha~ the ~ame
tre~ting capacity a~ the ~meltin~ furnace. Thi~ al~o
applie~ tc the ~ulfuric acid plant.
In the converter, unde~ired metal~ contai~ed
in the matte are oxidized by blowing air, and react~d
with a ~la~ formins agent added ~ch a~ ~ilicate ore
to tran~form them into the ~lag or eliminated by
vapori~ation. Sulphur in the ~a~te i~ also oxidized
by the blowing air to eliminate afi S02 ga~. Further,
- 3 -
~3~313~3
~olid material at roo~ temperatur~ ~uch a~ flu~ du~t
and ~crAp ~etal are added ~ cold charge ~or pre~ent-
ing the temperature ri~ing of the malt~
In the operation of the converter, th2 amount
o~ the matte charged at a time i~ limited by ~uch
factor a~ the inner volume of the converter. Con~equently,
th~ matt~ to be treated in one cycle i~ charged by dividing
into severAl portion~ although the copper ~rade of matte
i~ a factor. At each time of charging matte, the 31ag
forming a~ent and, i~ nece~sary, cold material~ are
charged~ When a major portion of the components to be
eliminated a~ slag are changed to the ~lag, the produced
slag i~ di~charged by tilting the converter. Then,
~upplementary matte and ~lag forming agent are charged
into the converter, and the treatment of the ~upple-
mentary matte is carried out and for~ed ~lag i~ di~charged
again. In the ~melting of nickel, the concentr~tion
of 25 to 30 percent nickel i~ further concentrated
through thi~ proces~ to about 75 percent. While in the
~meltin~ of copper, the white metal (Cu2S) obtained in
the above proee~s i~ further subject to copper forming
reaction to obtain the bli~ter copper.
The above individual period~ of ~lag forming
reaction3 ~nd the period~ of copper for~ing reaction~
are each commonly termed a ~tage9 ~ld a ~erie~ of the~e
individual 3tage~ i~ called one cycle o~ converter.
In u~e of the converter furnaoe, depending
on the treating capacity of the conv~rter ~urnace
against the ~melting furnace and number of the furnace~
in~talled two converter ~urnaces are ~lternately used
-- 4 --
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~53~
80 a~ to ~ave th~ down time between the completion
of copper forming period and th~ tran~fer to next
cycle, ~,hereby increa~ing the treating amount per
hour. To thi~ ~nd, many method~ have be~n propo~0d,
the method~ of which are, ~or cxample, cycle alternating
blowing method in which immediately after the aompletion
of copper forming period of one conYert~r ~urnace, another
converter furnace which i 8 r~ady for operation i~ .
s~cce~i~ely u~ed and the former converter furnace
~hich ~u~t compl0ted the copper forming rsaction gets
ready ~or next operation9 ~tage alternating blowin~
method in which two converter furnace~ ~re u~cd to
alternately e~ect the ~tage~; and method in which t~o
convarter furnace~ out of three furnace3 are alway~
under the operating condition for blowing.
The matte production 0peed of th~ ~melting
~urn~ce ~uch ~ fla~h ~melting furnace can be obtained
throu~h th~ material balance calculated from ~uch factor~
as the an~ly~i~ value~ of char~e, the amo~nt of charge
and the pre~et matte grade with r~fersnce to the
a~erage of the actual production rate. Th~ con~ert~r~
arc provided ~o that they Are sufficiently able to
proce~ the a~ount of matte produced by the ~melting
furnac~. The treating capaci*y of the converter i~
decidQd from the inner ~olu~ of the conv~rter an~ the
number of tuyer~ providod th~reto it. The period of
one cycle, though it diff~r~ dependin$ upon the Cu ~rade
of matte, i~ about 4 hour~ ~ith a nominal 28 to~s
furnace, about 5 hours with a nominal ~5-tons furnRc~
30 and about 8 hour~ ~ith a nominal capa¢ity of 150 to 180 t~nqO
.~ 5 -- .
~.~53~3~t~3
A~uming now that two nominal 200-tons
converter~ are u~ed as "cycle altern~ting blowing
method" wlth 585 ton~ of molten matte ~upplied from
the ~meltin~ furnace per d~y, the matte production
rate of the omelting furnace i~ balanced by three
cycle~ of matte treating if about 195 ton~ of matte
i~ treated in one cycle of about 8 hours.
If the matte i8 charged in two divi~ion~ into
the converter for each cycle, ~ith an actual weight of
molten matte of 120 ton~ charged for the first -qtage,
~nd the air supply i~ 3$arted at 0; 00, th~ amount of
matte to be charged for the ~econd ~ta~e i~ 75 tons.
A~sumin$ a period o~ 30 minute~ req~ired
between the end of the fir~t ~tage and the start o~ the
~econd sta$e for di~charging the slag and charging the
matte, a period of 40 minutes req~ired for discharging
the Ylag ~fter the end o~ the ~econd ~tage and a down
time of 20 minutes required between the end of the
third ~tage, iOe., the copper refining ~tage, ~nd the
~tart of the ~ir3t sta~e in the other ¢o~v0rter, th~
total blo~ing time in thi~ cycle i9
480 minute~ - (30 ~ 40 ~ 20) minute3 = 390 minut~.
In thi~ ca~e, the total air ~olume t~ be
~upplied for the individual ~tage~ are determined by
the theoretical air vol~me calculated from m~terial
balance taking the ratio o~ non-;reacted air and ratio
of leakage air into con~ideration and al~o empirically
R~:
60,000 Nm3 for the first ~tags,
3~ 55,000 Nm3 for the ~econd ~tag3
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~L~53~
100,000 Nm for the thir~ ~tag~.
In th~ third 3ta~e which i8 the copper forming
~tage, the oxygen in the supplied ~ir n~ed not oxidize
iron but i~ exclu~ively re~cted with thc ulur in the
~hite metal, ~o that the concentration of the S0? ga~
produced in thi~ stage i~ higher than that of the fir~t
and ~econd 9tage~. In the ~ulfuric ~cid plant, this
g~ withdrawn together with mixed air to m~ke the
S2 ga~ concentration and the introducing vol~me nearly
e~ual to that in the fir~t and ~econd stage~. F~r thi~
purpo~e, the blowing volume per unit time in the third
~t~ge i~ made to be 5 perce.nt le~ than, th~ rate in
the fir~t and ~econd ~t~ge8~ that i~ 95 per cent.
In thi~ ca~e, the di~tribution of blowing time,
~uch a~-tn pro~ide ~or an equal blowing r~te for the
individual ~tage~ follow~:
For the fir~t stage
= 106 ( )
0,000 ~ 55,000 ~ 100,000 ~ 0.95 mlnute~
For the ~cond ~tags
60~0-oo -~ 55--~-0-0-O-+-10~,00o ~'o.95 = 97 (minute~)
~or the third ~ta$e
100~00 ~ o~25 ~_~9~ ~ - 186 ~inute~)
' + 55~ + 10~00 ~ 0.95
Thu~, the ~cheduled ~tarting ~ndr~n~ time~
and blowing rate~ for the indi~idual ~tage~ of thi~
cycl~ are aR follow~:
3o
- 7 - . :
1~53~8
First ~tage Second ~tage Third ~tage
St~rting time 0;00 2:16 4:33
Ending t.ime 1:46 3:53 7~39
Blowing r~te 566Nm3/min~ 567Nm3/min. 537Nm3/min.
It i~ now a~umed that ~fter the fir~t stage,
the ~econd ~tage i~ started with ~n actual weight of
78 ton3 o~ molten matte charged in the converter at a
time of 2~23, which i8 delayed 7 minute~ from the
~cheduled time.
In thi~ ca~e, by lengthening the treating
period according to th~ amount of the matte ch~rged
in the oon~erter in exces~ of the ~chedule~ amount, the
rate of the matte productio~ in the smeltin~ furnace i~
balanced b~ th~ rate ~f treating in the converter. Al~o,
a~ the increa~e of the amount of charged matte re~ults
in the incr~a~e ~f the total blowing volume to be ~upplied
in the se~ond atage and the amount o~ ~hite metal to
be treated in the third ~ta~e, blo~ing ~olu~e ~or the
third ~tAge i~ increa~ed.
Thu , a period o~
1~205~578 ~ 24 ~ 60 = 487 (minute~
may be taken till the end vf this cycle. Becau e fir~t
25 ~tag~ start~ at 0:00, thi~ cycle end~ at ~:07. Since
20 minute~ i~ taken a~ the down time period after the
end of the third ~tage, i.e~, copper formin$ ~ta~e, the
and point cf thi~ ~ta~ is 7247.
Alao~ ~ince the do~n time of 40 minuta~ i
required between the ~econd and third ~tage3, the total
-- 8
: `
~53~
bl~wing ti~e Por both iffecond and third ~tage iiY
7 x 60 ~ 47 - (2 x 60 ~ 23) - 40 = 284 (~inute~)
Mean~hile, due to the increa~e of the
amount of matte, the tot~l air volume required for the
~econd ~nd third ~tage i~7 re-calculated to be
57,000 Nm3 for the ~econd ~ta$e
102,000 Nm3 ~or the third i~tage.
Thu~, the bl~wing timei~ for the econd ~nd
third stage~ are re-determined ~imilar to the previouis
dii~tribution to be ai~ ~ollow~:
For the i~econd ~tage
57,000 ~ 102,000 ~ 0.95 = 98-5 ~ 99 (minutes)
For the third stage
5j i0o1jO0Oo2 oo95~xo2~54 = 185.5 _ 185 (minute~)
Thui~, the re-schedule ~n and ~fter the ~cond
tsta~e iY ai~ follow~:
Second ~tage Third stage
Starting time - 2:23 4:~2
Endin~ *ime 4:02 7:47
Bl~w~;ng rate575 Nm3/min. 549.4 Nm3/min.
It i~ now a~i~umed that the atar*ing time o~
:, . .
third i~ita$e after ~lag of~ in the second ~tage is 4:38,
4 minute3 earlier th~n the ~cheduled time~ In thiis
case, it iii~ nece~Yary to reduce the blowing rate ~or
correi~pondin~ the endin~ time to the i~ehedule time.
Accordingly9 the blowin~ rate i~
1027000 ~ (l8s ~ 4) = 539.7 Nm3/min.
By Dper~ti~lg the co~verter ln the above w~y,
the tr~i~tment of matte in the conv0rter can bs cArried
_ 9 _
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~53~g`~
out in keeping balance with the a~ount of matte production
in the ~melting furnace, and also it i~ po~ible to
provide for oub~tantially uni~orm ~upply of the S02 ga~
to the ~ulfuric acid plant.
The air blowing into the converter i8 made
through ~ number of tuyeres provided in the ~ide wall
of the converter. Since solid matter build~ up at the
opening of each tuyere opened to the interior of the
refractory brickY and eventually clo~e~ the tuyera,
during the blowlng, th~ ~olid matter i~ frequently
removed by ~ punching rod from the out~ide into the
interior of the furnace to provide for ~ufficient blow-
ing.
Since the blocking of the tuyere~ varie~
depending upon their location, temperature distribution
withi~ the ~urnac0 and other variou~ factor~, the
blowing rate into the converter i~ ~ubject to Pluctuation~.
There~ore, occurrence of difference between
~cheduled total blowin~ ~olume and actual blowin$
volume i~ unavoidable, cau~in~ deviationY of the ~cheduled
blowing~;time ~or completing the converter reactionO
If one cycle ends earlier than a ~shedul~d time, it
mean~ a hi~her average blowing rate than the ~cheduled
rate. I~ this ca~e, excessi~e ga~ i3 ~upplied to the
~9 sulfuric acid pl~nt, and the S~2 tre~t~ng cap~city of the
sulfuric acid plant ~o~Qd-b~ ~ometimcs ~urp~s~ed. Al~o
~ince the matte production rate in the smeltin$ furnace
i~ not chan~ed, the down time in *he operatio~ of the
converter io extended, leading to increa~ed heat lo~s
till the otart of the ne~t cy¢le. Fuxther, ~ince the
,
- ~53~
capacity of the sulfuric acid plant is fixed, an increase
of the converter exhaust gas volume beyond a scheduled
volume forces reduction of the exhaust gas from the
smelting furnace, necessarily leading to reduction of the
eed rate of ore to the smelting furnace.
On the other hand, if the cycle takes a longer time
than the treating time corresponding to the amount of the
charged matte, the treating capacity of the converter
becomes insufficient with respect to the smelting furnace,
so that it becomes unavoidable to reduce the matte
production rate in the smelting furnace, which also leads
to insufficient supply of exhaust gas to the sulfuric acid
plant and results in the reduction of the conversion
efficiency. If such fluctuations are taken into
consideration, considerable redundancy has to be provided
for the capacity of the plant which is inefficient from
the standpoint of the equipment economy.
This invention has an object of providing a method of
operating one or more converters, which permits to keep
well balanced with smelting furnace and sulfuric acid
plant and to exhibit fully as possible the capacities of
the related equipment.
According to the invention there is provided a method
of operating at least one converter furnace for treating
molten matte, which comprises adjusting the blowing air
volume supplied per unit time within a predetermined range
such that the supply of a scheduled total blowing air
volume for one of a plurality of stages of one cycle in
the converter operation ends at or close to a scheduled
end time of the blowing for said stage, said adjustment
being effected by subtracting the real blown air volume
. i, ,,: .: -
53~
from said scheduled total air volume at a suitable time
between the start and end of said stage to obtain a
remaining air volume and adjusting the blowing air vclume
supplied per unit time to ensure that said remaining air
volume is completely supplied at or close to said
scheduled end time.
The invention will now be described in conjunction
with an example thereof. `. ;
Example
The amount of molten matte supplied from a smelting
furnace into a-converter was 591 tons per day. This matte
was treated in the converter in three cycles,
~ .
-
- lla - ~
1~5~
that wa~, 197 ton~ of matte was treated in each eycle
with a treating time of 8 hours. Similar to the above
di~cription, the blowing time in ona cycle excluding the
down time wa~ #et to 390 minute~;
Al~o, ~cheduled total air volume ~ere
61,500 Nm3 for the fir~t ~tage
55,000 Nm for the ~econd ~tage
101,000 Nm3 for the third stage.
The amount~;of matte charged for the fir~t
~tag~ wa~ ~et to be 122 tons, ~ith the matte amount for
the s~cond stage being thu~ set to 75 tonY. Similar
to the above, the bl~wing time~ in the individual ~tages
allotted ~o tha$'~the blowing rate per unit time WA
~ifor~ were a~ follow~:
For the fir~t ~ta$e
61~500 + 55,000 + lo1,ooo ~-0.~5 = 108 (minute~)
For the ~econd ~taga
61~500 + 55.~00 + lO1,Ooo x-0-.95 = 96 (minu*e~)
For the third ~tage
. 101?000 ~ 0.95 x 390
~1,500 ~ 55,000 ~ lb~,000 x-0.95 = 1~6 (mlnute~)
Thun, the ~chedul~d starting and ending tim~s
and blo~ing rate~ for the indi~idual ~tag~ were ~et
a~ follo~: .
~ir~t ~taga Second stage Third stage
Starting time 3:20 5:38 7:54
~ndin~ time 55o8 7:14 11.00
Blowinggrate 569 ~m3/min. 573 Nm3/~in. 543 Nm3/min.
_ 12 -
~0530~B
At 4:15 after the start of the first stage,
the re~l blown air Yolume wa~ found to be 30,389 Nm3.
At this time, there was left 53 minu*e~ until the
ocheduled time of end of thi~ ~tage, and the total air
volume of remaining to be ~upplied was 61,500 ~ 30,389 =
31,111 Nm3. Gon~equently, the aub~equent blo~ing rate
W~8 adjusted to 31,111 ~ 53 = 587 Nm3/min.
Since the range of the blowing r~te we~ ~et
to be 530 to 600 Nm3/min., ~he rate of 587 Nm3/min.
10 waff olightly below the upper limit of blowing rate,
the blowin~ was continue~ at that rate, which was
thereafter repea*edly adju~ted at an inter~al of 5
minutes. At the time of eaoh o~ these adju~tment~, the
new rate WA8 within the afore-men-ioned predetermined
rat~, ~o that the fir~t ~tage could be ended at the
~cheduled e~ding time.
After the fir~t stage and di~charging the
~lag, 77 ton~ o~ m~tte wa~ charged into the converter,
And the bl~ing for the second stage wa~ ~tar~ed at
20 5:36.
Since the ~mou~t of the charged matte and the
~tarting time of the serond ~ta~e dif~ered fro~ the
~cheduled on0a, the corrected ending ti~e of the third
~tage wa~ calculated.
12259177 x 1440 = 485 (minute~)
Thus, the c~rreeted ending time of the +hird
stage wa~
3s20 + 485 minute~ - 20 mi~utes = il:05
Al30, with the increa~e of the ~a*te, the
- 13 ~
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.: " .. . , , , , . ~ :
~53~
~cheduled total air volume~ for the ~cond and third
~tage~ were altered to be
57,000 Nm3 for the ~econd ~tage
102,000 Nm3 for the third ~tage.
The total blowing time for the ~econd and
third ~tage~ was
11 x 60 ~ 5 - (5 x-60 + 36) - 40 = 289 (minutes)
~nd the di~tribution of thi~ time wa~
57.000 + 102,000 ~ o.95 = 100 ~minute~)
~or the ~eoond ~tage
and
102,000 ~ 0.95 x 289
57,000 -l~102,00o ~ 0.95 = 189 (minute~)
for ~he third tage
From the above, the ~chedule on and ~fter
~econd ~tage w~ altered to be a~ follow~:
Second ~tage Third stag~
Starting time 5:36 7:56
Endin$ time 7.16 11:05
Blo~ing rat~ 570 Nm3/min. 539 Nm3/min.
In the ~econd ~tage, similar to the fir~t
~tage, the blowing rate wa~ adJu~ted at the interval
of S minute~ by obtainin~ the re~l blo~n air volume for
the 3tage, ~ubtracti~g thi3 volume from the scheduled
total air volum~ to be ~upplied for thi~ stage to
obtAin the total air volume o~ the remaining, and
dividing the l~t obtain~d volume by the r~idual ti~e
o~ this stage. At 6:21, the real blown air volu~e wa~
~ound to be 23~120 Nm3. At this tim~, the rem~ining
time until the ~nd of thi~ ~tage wa~ 55 minute~, ~o thAt
- 14 w
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~53~
for ending thi~ ~t~ge at the ~ched~led ending tim0,
the blowin~ rate had to be made to
(57,000 - 23,120l ~ 55 = 618 Nm3/min.
Howev0r, ~ince the s~eltin~ furnace and
~ul~uric acid plant were combined with th~ upper limit
of the blowin~ rate ~et to 600 Nm3/min., if blowing
effected at thi~ upper limit, the ending time of thi~
~tage would be extended and~lwould result in out-of~
balance with reApect to the ~melting furnance.
Accordingly, the aver~ge blowing rate for the re~t
of the cycle wa~ calculated by addi~g 55 minute~, the
remaining blowing time o~ thi~ ~tage, to 189 minute~,
the ~cheduled blowing time of the third ~tage, adding
33,880 Nm3, the total air volume of the remaining to
~5 be su~plied for this ~tage~ to 102,000 Nm3, the total
air volume to be ~upplied ~or the third ~t~, and
dividin~ the seGond ~um of 135,880 Nm3 by the fir~t ~um
of 244 minute~ (and taking the m~a~ure for redu~ing the
blowin$ rate as the rea~on ~hat the third ~ta~e wa~ the
c~pper ~srming st~$e as mentioned earlier).
33 ~80 ~ 102 000 ~ 0.95 3
= 579 (Nm /man~)
By thi~ value, the tot~l air voluma of the
remainin~ for the sec~nd ~tage ~a~ divided to ~btain
the rem~ininS blowing tim~ ~or the ~econd ~ta$e.
33,880 ~ 579 = 59 (minute~)
By thi~ v~lue, the total ~ir volume o~ the
remainin~ for the second ~tage wa~ divided.
33,880 ~ 59 = 574 (Nm3/min.)
The blo~ing rat~ wa~ adju~ted to thi~ value and similar
'~5 ~
.. . : . ... : .... ~ ., :.,
1~530QB
Adjustment3 were made at the interval of 5 minute~.
In thi~ way, the second stage wa~ended 2 minutes ~fter
the ~cheduled ending til~e.
To ~ecover thi~ delay during the third ~tage,
the blowing time of the third ~tage wa~ ~horte~ed by
2 minute~ to 187 minute.~, And the third ~tage wa3
~tarted a-t 7:48, ô minute~ later than the ~cheduled
time, at blowing rate of
102,000 ~ 187 = 545 (N~3~min.)
The upper limit of blowing rate for the third
~tage had to be kept to 0.95 time~ the previou~ upper
limit of 600 Nm3/min., that i~,
600 x 0.95 = 570 (Nm3/min.)
Thu~, the blowing wa~ actually made at a ~ate
clo~e to the upper limit, namely,
102,000 ~ (187 - 8l = 569.8 (Nm3Jmin.~
At 9:30 the real blown air volume ~upplied
for thi~ ~*age wa~ 45,000 Nm3, which wa~ le~ than the
~cheduled volume. EYen at thi~ time, the blowing rate
w~q ~et to the ~pper limit of 570 Nm3jmi~. for the
third 3tage.
Thu~, the remaining blowing tim~ wa~
102 9 570 45~~ = 100 ( minut e ~ )
Although thi~ time meant that the ~cheduled time was
e~ceeded by 5 minute~, ~aid del~yed ending time W8
clo~est to the scheduled ending time of blowi~g for thi~
~tage ina~much a~ the blowing rate was held within the
predeterminad range.
Although in the above de~cription of the
- 16 -
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. . .. . . ..
~5~
example, the correction of the ~cheduled blowing air
volume when there is a dif~erence of thoaamount and
composition of the actually char~ed cold material with
re~pect to A scheduled ons ha~ been omitt~d for the
Dake of ~implicity of the de~cription, in the actual
operation such corre~tion is al-qo made.
Al~o, while the above example ha~ concerned with
the case of converting the copper matte into bliqter
copper, in the case of dealing with the niokel ~atte
the blowing rate i3, in the l~t 3tage, not reduced
from that in the praceding ~t~geq ~ince the conccntration
of the nickel grade is aolely effected~ This situation
al30 i~ applicable to the case ~f dealin$ with copper
matt~ to produce white metal but not to produce the
blister copper. Further, ev~n in the ca~e of producing
the bli~ter copper, with som0 ~tage~ carried out by
simultaneouoly operating a plurality of co~erter~,
the copper forming stage may be carried out without
reducing the blowlng rate compared to the preceding
Ytage~ becau~e it i~ po~sible to uniformalize the gA~
conoentratlon combining the exhau~t ga~ ~rom one
converter with that fr~m ano~her converter.
In c~rryin~ out the invantion~ the nece~ary
calculation~ can be effected by u~ing an electronic
comput~r, and it i~ po~ible to perform automatic
operation by combining th~ computer with aut~matic
control equipments. Thu~, by so ~rran~in~ a~ to ad~u~t
the blowing rate at a fix~d inte~val, for in~tance 5
minuteq, the operation may be preeis01y oarried out
according to *he -~chedule. Furth~rmore, it is pos~ible
~053~
to keep (furnace condition) con-Qtantly by varying the
tuyere punching frequency accordin~ to the blowing
rate.
A~ ha~ b~en de~cribed, ~ince accordin~ to
the invention the blowing rate i~ controlled a~ to
end each stag~ at the ~chedu:Led time according tv th~
total air volwne of the remaining to be supplied in
the operation of each stage, while keeping the variation~
of the blowing rate within a predetermined range, the
matte tr~a*ing rate in the converter may be ad~pted
to comply more ~trictly with the ~atte producing rate
in the ~malting furnace. Thu~, it i~ pos~ible to
improve the operational stability of the ~melting
furance, and to minimi~e the variation~ of the rate
f ~upply of S02 gA~ from the converter and ~meltin~
furnace to the ~ul~uric acid plant, ~o th~lthe varia-
tion for the operational conditiQ~ of the~e equipm~nts
may be reduced compared to the conventional method.
Thu~, lt i~ po~ible to increa~e the treating capacity
of ths ~meltin~ furnace and ~ulfuric acid plant.
Al~o, as ha~ been ~hown in connection with
th~ ~ec~nd stage in the ~bove example, if there i~ any
remaining ~tage~ by ~o arran$ing a~ to adjust the
blowin~s rate for present :stage by adding the tt~tal ~4ir
volume of the remaining to be 3upplied for ths pre~ent
sta$e and the total air vQlume to b~ ~upplied for the
re~aining ~tage or ~tages, the time required for the
whole cycle may be adju~ted more readily compared to
the ca~e of adju~ting the blowin~ rate ~ithin the
30 individual qtage~ .
-- 18
~L~53~
Of cour~e, ~ince the ending time~ of the
individual ~tag~ and the cycle can be indicated, the
preparation~ for the sub~equent stage or cycle may
be made on the ba~i~ of th~ indications~
In the caae of the cycle alternating blowing
method, the variation of the down time betw~en cycle~
i~ reduced in the caqe according to the inven*ion
compared to the conventional case aa is shown below.
Average Variance Standard Coef`ficient
. value deqiation of VariRnCe
Conventional 17.86 115.4 11.01 61.6%
method min. min. min.
Method accord- 18.52 69.1 8.51 46.0%
ing to the min. min. min.
invention
15 Since accordin~ to the invention the
fluc$uation~ of the volume of the converter exhau~t
ga~ are greatly reduced, even ~ith the maximum volume
of converter exhaust gas, the ~um of the volu~e of the
conv~rter e~hau~t ~as and the volume of the ~la~h
~meltin~ furnace exhaus* gas may be le~s than the
maximum suction capacity of the ~ulfuric acid plant
if the ~melting amount and exhau~t ga~ volume of the
~la~h smelting furnace are constant. The compari~on
of the varia~ions of the copper convert~r exhau~t ~aa
volume between the ca~e according to the invention and
the conventional ca~e in term~ of numerical figure~
wa~ follows.
- 19
~ ~53~38
Average Variance Standard
Nm /h. Nm /h. deviation
Nm /h.
Con~ention~l method
FirYt ~lAg ~ormation55 x 103 13.0 x 106 3.609 x 103
~; ~tage
Second alag 61 x 103 24.9 x 10~ 4.990 x 103
formation ~tage
Copper forming 61 x 103 89.5 x 106 9.460 x 103
~t~g~
Method according to
the invention
~ir~t ~ag 62 x 103 4.9 x 10~ 2.213 x 103
formation ~tage
Second ~lag 59 x 103 5.0 x 106 2.236 x 103
formation ~tage
Copper formin~ 60 x 103 2.6 x 106 1.612 x 103
4tage
In this ca~e, the rate of smelting in the
fla~h ~melting ~urnace was 42 ton3/h., the volume of the
flaah smelting furnaoe exhaust ga3 wa~ 80 ~ 103 Nm3/h.,
~nd the ~uction capacity of the .qulfuric acid plant waY
160 x 103 N~3/h. In the ca~e of the conventional
method, the total volume of a~hau~t gas withdr~wn into
the ~ulfurie acid plant during the first or ~eoond slag
for~tion ~tage of con~erter is below the suction
capacity of the ~ul~uric acid plant, namely 160 x 103
~m3/h., even i~ av~ra~e volume of the exhaust gas in
the flash ~melting ~urnace, and the ~xhauat ga~ in the
converter, and thrae time~ the standard deviation o~
the exhaust ga~ volume in the converter are added
together. However, the variati~ are lar~er in the
copper forming ~ta~e than in other ~tage; the ~um o~
the averaxe volume exhau~t ga~ in the flaah ~elting
- 20 -
. . . . . . .
~053~
furnac~, exhaust ~sas in the converter, and 2 time~ the
standard de~riation of the exhauslt ga~ rolume in the
converter i~ 159.92 x 103 Nm3/h., ~ubstantially
corre~pond to the suction capacity of the slllfuric
acid plant~ In the ca~e of the conventional tnethod,
there iq no redundancy of the smelting amount of the
fla~h smelting furance, and al~o in the copper forming
stagQ of the con~rerter it i~ liable that the sum of
the exhau~t gaE~ volume in the fla~h ~melting furnace
and converter exceeds th~ suction capacity of the
~ulf`laric acid plant.
In contrast, in accordance with the in~rention,
the ~um of the a~rerage volume of the flaElh smelting
furnace exhau~t gas and converter exhaust ga~, and th~ee
time~ the ~tandelrd deviation of the exhaul3t ~as volume
in the con~rerter i~
148.639 x 103 Nm3/h. in the fir~t ~a~ formation
tag~,
145.708 x 103 Nm3/h. in the ~econd slag formation
~ta~e, and
144 r 836 x 103 Nm3Jh. in the copper forming ~tage.
Thus, a redundancy of 11.361 x 103 ~Im3/h.
even in the first slag formation ~tags ~here the total
volume of the e~au~3t ga~ i~s th~ highest one in
25 compari~on ~ith the su¢tion s:apacity of the ~uLPuric acid
plant, namely 160 x 103 Nm3~h., is pro~ided.
Consequently, in thi~ ca~e it i~ pos~ible
to increai3e the 0~hau~st ~ voluma by increa~ing the
~melting amount in the fla~h smelting ~urnace.
30 (If n~ce~3s~lry, it i~ poe~3alble to operate the c~n~rerter
- 21 _
. , .:
~615;~
at the ~ame required air volume rate, while increasing
the copper content in the matte by rai~ing the copper
~rade of th~ matte with increa~ad smeltin~ amount in
the flaoh ~meltin$ furnac~)~ In a comparative ca~e
o~ incre~ng the ~melting amount in *he ~la~h smelting
furnRce where matte of the ~me copper grade a~ the
conventional one i8 produced, the productiDn amount
of matte in the flash ~malting furnace i9 increa~ed,
calling for an increa~e of the air volume to b~
~upplied to the converter ~nd hence leading to incre~e
of the conYerter exhau~t ga~. If in thi~ ca~e the
redundancy of the ~ulfuric acid plant i~ to be filled
with the total ~xhau~t ga~ ~olume from the fla~h
~melting ~urnace and converter, the tot~l exhau~t ~a~
volume ~or 1 ton/hr. of the ~melted materi~l to the
fla~h -~melting furnace is
148.639 x 103 4 42 = 3.54 x 103 (Nm3~h.)
and hence increa~e of the ~malting capacity is
11.361 x 103 ~ 3.54 x 103 = 3.2 (tons/h.)
Henca, t~e amount ~f the fe~d m~terial i~
42.0 ~ 3.2 = 45.2 (to~/hr.)
Thi~ mean3 that it i~ po~ible to incre~e *he ~malting
cap~cigr by about 7.6 percent.
- 22 -
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