DE1066214B - Method and device for disarming pyrite in a deck furnace - Google Patents

Description

GERMAN

REGISTRATION DATE: J A N U A R 1958

NOTICE THE REGISTRATION AND ISSUE OF THE EDITORIAL:

!. OCTOBER 1959

According to a proposal that is not part of the known prior art, the throughput of a deck roasting oven can be increased considerably by virtue of the fact that the gas mixture penetrating the oven is withdrawn from one or more floors during the roasting process, one outside of the oven Releases part of its heat content in such a way that it can be used, preferably for steam generation and the discharged gas is returned to the furnace on the floor above. This measure allows not only an increase in throughput, but also the production of a more concentrated one Roasting gas and the utilization of a larger proportion of the roasting heat "for steam generation than the known procedures.

According to this proposal, the gas leaving the top floor of the roasting furnace becomes better known per se Way passed through a second waste heat boiler, which can still use the remaining heat content of the roasting gases power.

The invention is a further improvement of this unknown proposal, which It allows an equally high amount of steam and an equally high roast gas concentration with a single waste heat boiler and to achieve an equally high throughput.

According to the invention, the deck oven is operated in such a way that a pre-roasting part and a post-roasting part each operated individually in an optimal way. Of course, it is advisable to and to combine the roasting part structurally into a single unit. In the upper or pre-roasting part is exclusively or predominantly only to the reaction method and device

for the disarmament of pyrite

in the deck oven

Applicant:

Metallgesellschaft Aktiengesellschaft,
Frankfurt / M., Reuterweg 14

Dipl.-Ing. Rudolf Hess

and Dipl.-Chem. Dr. Günter Friese, Frankfurt / M.,
have been named as inventors

2 FeS ₂ + 2

: 2 FeS + 2 SO,

(I)

worked towards it, while in the post-roasting part mainly the reaction

2 FeS + - ^ - O ₂ = Fe ₂ O ₃ + 2 SO ₂

(Π)

is carried out.

It is known per se that the roasting of gravel always proceeds via these two stages, but are So far deck ovens have not yet been operated in such a way that each of these two stages is optimal for itself Way is operated in such a way that the gas paths for both stages are separated.

According to the invention, the roasting gas is withdrawn from the post-roasting stage at a point where the temperature is as close as possible below the maximum permissible, which is around 800 ° C for most gravel. This gas has an SO ₂ concentration of around 8 to 9% and is fed to a single steam boiler together with the roasting gas produced in the pre-roasting stage. The pre-roasting stage is fed partly with fresh air and partly with cooled cycle gas, which is branched off behind the steam boiler. Since both gases are cold, enough heat is withdrawn from the pre-roasting stage in this way so that the maximum permissible temperature is not exceeded. Since practically only sulfur is burned in the pre-roasting stage, it is possible _{to achieve an SO 2} concentration of up to 21% in this stage, and the combined roasting gas from both partial flows therefore has an SO ₂ concentration of 14 to 16%.

According to a particular embodiment of the invention, the known per se is used Return of the warm air from the stirring shaft equalized in the oven, the temperature level in that the lower floors of both roasting parts, the tend to take a lower temperature than the upper floors, brought to higher temperature will.

Since the excess roasting heat is dissipated outside the oven by the gas flow according to the invention and can be made usable, in contrast to known deck roasting ovens, it is possible to use the The furnace should also be designed to be thermally insulated and thus the portion of the roasting heat that is used for steam generation is harnessed to increase even further.

The invention is illustrated schematically and in greater detail, for example, with reference to the drawing.

The gravel to be rusted is fed into the multi-storey furnace 2 through the feed hopper. This consists of a pre-roasting part A and a post-roasting part B. The roasting air is fed into the oven by the fan 3.

909 630/145

brought. According to the embodiment shown, it is fed exclusively to the hollow agitator shaft 4 and supplied as warm air to both the pre-roasting and post-roasting zones on the lowest floor. The roasting gas is drawn off through line 5 from the top floor of the post-roasting zone and sent to the waste heat boiler 6 supplied. Likewise, the exhaust gas from the uppermost layer of the Vorröstzonc is through line 7 withdrawn and gives the NVichröstzonc its heat content in the steam boiler 6 together with the roasting gas away. Part of the cooled roasting gas is drawn off as production, another part by fans 8 back to the lowest level of the pre-roasting zone. The burn-up is carried out through the discharge 9.

The furnace is protected against external heat losses by the insulation 10.

The ratio of circulating gas to fresh air in the Nachröstzonc is dimensioned so that the temperature within the individual floors as possible just below the maximum allowable Hegt. When the circulation gas is cooled to 350 ° C, there is a ratio from circulation gas to fresh air of about 1: 1 is optimal. To get the best results, you have to Pre-roasting and post-roasting are separated from each other in terms of gas. Any known Schlcusenkonstruklion can be used, which allows the gravel to fall through, but allows the Gas prevented. But it is also possible, a small part of the roasting gas from the Nachroststufe in the Let the pre-roasting stage pass.

Claims (4)

Claims. 1. Procedure for disarming pyrite in deck ovens, characterized in that the gas mixture penetrating the furnace approximately in the middle of the Oven is removed at such a point where the reaction 2 FeS ₂ + 2 O ₂ = 2 FeS + 2 SO ₂ (I) has just ended, given up to a steam boiler together with the exhaust gas from the top floor of the furnace and a partial flow from the gas leaving the steam boiler into the floor of the furnace is returned, which is above the lower gas exhaust, and fresh air on the same floor is fed. 2. The method according to claim 1, characterized in that as fresh air for the deck oven in In a manner known per se, the warm air obtained during the cooling of the Rührwellc is used. 3. Device for performing the method according to claims 1 and 2, consisting of a deck oven, the upper and lower parts of which are separated from each other in terms of gas, each with a gas extraction line from the upper floors of the upper and lower part, a common feed of these two gas flows to a steam boiler and a return line from the production gas line to the lowest floor of the upper part. 4. Apparatus according to claim 3, characterized by thermal insulation of the multiple-hearth furnace. 1 sheet of drawings O 909 630/145 9.59