FI63067C - TILLVAEGAGAONGSSAETT VID FRAMSTAELLNING AV SINTRADE KULOR AV METALLOXIDHALTIGT AEMNE - Google Patents

Description

RSSr ^ l [B] (11) ADVERTISING PUBLICATION, n, „'Kg / ft LJ' 'UTLÄGGN I NGSSKRIFT OOUO l C (45) Patent granted 11 04 1933 Patent meddelat x * (51) K * .ik.3 / I «.A.3 c 22 B 1/14

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(23) AlkupUvt —GlMihradig 2γ 03 7l (11) Tullut julkiMksI - Bilvlt affamlig

National Board of Patents and Registration (44) Nlhank.l ^ on | «kueLMIutaun ρηη.- O'o '

Patent- och registrrtyrelsen Amttkan utlagd ocfc utUkrtftsn pubilcend 31 · 12. o 2 (32) (33) (31) Requested privilege —8 «| * rd prtoritet 13. CA. 7 3

Norway-Norway (NO) 15 ^ 6/73 (71) Elkem a / s, Middelthuns gate 27, Oslo 3, Norway-Norway (NO) (72) Hans Skretting, Vägsbygd, Norway-Norway (NO) (7 ^) Oy Kolster Ab (5 ^) Method for making sintered balls from a metal oxide-containing material - Tillvägagängssätt vid framställning av sintrade Kulor av metalloxidhaltigt ämne

The invention relates to a process for the production of sintered, metal oxide-containing balls, and more particularly to the production of mechanically strong balls containing iron, manganese, chromium and the like. oxides by sintering in a shaft furnace.

When sintering in a shaft furnace, the raw balls are normally taken directly to the top of the shaft furnace so that the balls gradually become dried and burned as they descend down the shaft. However, some types of balls, especially those made of a very fine-grained material, tend to explode into pieces and powder if heated too quickly in the drying zone of the shaft. This can cause major malfunctions in the shaft furnace and thus a reduction in production.

Another difficulty is that raw balls can often clump together at the upper end of the shaft into bundles, which can then sinter together at the lower end of the shaft into formations that can cause interference in the shaft. This is especially the case when very wet balls are sintered, e.g. made from too moist concentrate, and when for some reason the balls have become too small. In these cases, it is often necessary to lower the temperature of the shaft as well as the 2,63067 feed rate to reduce sintering formations, but this in turn causes mechanically weak balls and reduced production.

The inventor has found that these disadvantages can be avoided if the balls, before being fed into the shaft, are pre-dried in a separate dryer in which the balls are required at 150-500 ° C until their moisture content does not exceed 1.5 i. has achieved a compressive strength of about 15 kg for dry balls. Using less sulfite liquor + some bentonite, a compressive strength of 9 kg was obtained. When using such pre-dried spheres, the capacity of the shaft furnace used has been obtained 2.5 times the normal capacity. This means that with the method according to the invention the capacity of existing plants can be more than doubled. The shaft furnace can also be operated at a higher operating temperature without the balls breaking or causing sintering formations. In addition, better and more uniform quality of the manufactured balls was achieved. Fuel consumption in the shaft per ton of bullets was also reduced. The sintering temperature can be about 1000-1500 ° C, depending on the composition of the raw materials and the softening temperature.

In addition to sulphite lye and bentonite, molasses or another known binder or a mixture thereof can also be used.

Example:

The magnetite concentrate, ground to 10,000 cm / cnr (about $ 99 + 200 mesh), was ball sintered with the addition of about 2 L of sulfite liquor and water to give the crude cubes a moisture content of about $ 6. The compressive strength of the raw balls was about 1 kg. The crude balls were dried at about 170 ° C in a separate dryer to a moisture content of about $ 0.2. The dry balls were then fed to the top of a sintering shaft where they were gradually heated to about 1200 ° C. The sintered spheres had an average compressive strength of 105 kg and a wear resistance of 85 l. In both cases, about 5,000 kg of balls were produced per hour, which is three times the normal capacity achieved with the same type of raw balls. Fuel consumption was about 9 kg of oil per tonne of bullets, while the corresponding amount is about 15 kg / t when sintering the corresponding crude balls.

In the above description of the invention, there has been talk of ball sintering of finely divided ore or concentrates, here a feldspar roast, but other finely divided material, e.g. dust, waste, etc. can also be added to the balls.