DE1937324B2 - Process for processing non-ferrous metal-containing sulfur pebbles by means of chlorinating volatilization - Google Patents

Description

2. The method according to claim 1, characterized in that that the lowering of the sulfur content can already be seen in the aggregates of the gravel pebble roasting undertakes.

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The present invention relates to a method for improving the quality of the work-up Non-ferrous metal-containing pebble burns by means of iron ore pellets arising from chlorinating volatilization.

In the last few years there have been processes for reprocessing gravel burns, i. H. for removal the accompanying non-ferrous metals and for the transfer of the remaining iron oxide component in a form suitable for blast furnaces, made known by means of chlorinating volatilization. Included the chlorination can either be carried out by solid chlorinating agents involved in the burn-offs, e.g. B. calcium chloride, or else by means of gaseous chlorinating agents, preferably chlorine or hydrogen chloride will.

In the first process, fine-grained, normally ground burns are added pelleted from calcium chloride and then after drying at about 1200 to 1300 ° C, the non-ferrous metals are volatilized as chlorides (Stahl und Eisen, 76 [1956], pp. 588 to 595; GB-PS 6 96 664 and Sulfur, No. 77, July / August 1968, pp. 34/35).

With the other methods, the burns are pelletized after grinding and the dried ones Pellets treated in a multi-zone single-shaft furnace. Here are in the upper part of the furnace shaft the pellets burned hard, the non-ferrous metals in the middle part volatilized with a chlorine-air mixture and in the lower part of the furnace shaft the pellets are cooled with air (Erzmetall, XX [1967], issue 1,

Pp. 7 to 13). ...

The sulfur content of the burn-up to be processed is normally in the range of about 2.5 to 6% total sulfur, with the majority almost always in sulfidic form (ore metal, XX [1967], Hefl: 11, b. 50.3).

In the investigation into chlorinating addiction after both of the processes mentioned, it has now been found that the sulfur content of the reacted Burn-offs, especially the sulphide-sulfur content, have a significant influence on the achievable pellet strength and, albeit to a lesser extent, on the volatility of the metals. With lower ones Sulfur contents are always more favorable results, often a work-up only after the sulfur content has dropped below a certain level, depending on the type of burn dependent value is possible.

In order to achieve these favorable results, the sulfur contents are therefore used according to the invention the normal non-ferrous metal-containing pebbles burn before the firing and chlorination process by roasting below the usual values, preferably to <2.5 »/ o total sulfur and <1% sulphide sulfur, lowered.

The examples listed below, in which the original burn-off (I) and for comparison the same burn-up after lowering the sulfur content through post-roasting (II or III) the process are subjected to chlorinating volatilization under the same conditions, the Show the importance of the invention.

example 1

In a Rio Tinto burn with 2.90% total sulfur (1.95 »/ 0 sulfide sulfur), 1.69» / 0 Cu, 3.43% Zn and 0.66% Pb (I), the sulfur content became reduced to 0.65% total sulfur (0.12% sulphide sulfur) through post-roasting (II).

These burns I and II were ground to the same fineness (I = 3350, II = 3250 cm ² / g according to Bl aiη e), pelletized with water, then burned under the same conditions and then chlorinated. The following table shows the results:

NF content and pellet strengths of the chlorinated burns I and II

Firing temperature
in ⁰ C

»/ OCu

° / oZn

° / oPb

kg / pellet

I. II I. II I. II I. II 1100 0.006 0.007 0.13 0.15 0.08 0.09 32 104 1150 0.07 0.03 0.43 0.28 0.10 0.05 46 156 1200 0.17 0.10 0.72 0.59 0.13 0.05 33 202

With the sulfur-rich burnup I, 65 len can be achieved. On the other hand, in the case of the lower sulfur burnup II

despite the increase in the firing temperature from 1100 to

1200 ° C nowhere near sufficient to good for use. Also with

Pellet compressive strengths required by blast furnaces achieve burnup II in contrast to the more sulfur-rich ones

Burn-off at the stated firing temperatures is even more favorable, d. H. lower, non-ferrous metal residues achieved.

Example 2

A pyrrhotite burn with 0.78% Cu and 2.83% Total sulfur (2.15% sulfide sulfur) (I) was reduced to a level by post-roasting in one case (II) of 2.09% total sulfur (1.39% sulphide sulfur) and in another case (III) to 0.67% total sulfur (0.10%> Sulphide sulfur) brought

This burn-ups I, II and III were milled to approximately the same particle fineness (3250-3550 cm ² / g according to B1 ai π e) and in each case after the addition of 2 "Vo lime with a calcium chloride solution (300 g / l) pelletized. The pellets were after drying, fired under the same conditions.

The following list shows the residual copper content and the compressive strength of the fired pellets:

Burn-off

Residual content Cu
in Vo

Pellet strength
in kg / pellet

III

0.35
0.15
0.07

95
120

225

The results show that the quality of the fired pellets decreases with decreasing sulfur content in the initial material (I - * - II -> III) both with regard to the pellet strength as well as the non-ferrous metal volatility is significantly improved. In the example only the low-sulfur burnup III is in work up satisfactorily by this method.

Claims (1)

Patent claims: 1. Process for improving the quality of non-ferrous metal-containing materials in the work-up Gravel burns by means of chlorinated volatilization of iron ore pellets, thereby characterized that the sulfur content of the burn-ups before the burning and chlorination process is below 2.5 »/» total sulfur and 1% sulphide sulfur removed by post-roasting