NO123576B - - Google Patents

Description

Mixture for treating molten iron.

The present invention relates to a mixture intended for the treatment of molten iron. The mixture is particularly suitable for the production of nodular iron. However, it can also be used in other compounds, such as in the desulphurisation of iron.

In the production of nodular iron by alloying magnesium

is it common to use pure magnesium or alloys with different amounts of magnesium such as FeSiMg, NiMg or the like. Several methods have been used to introduce the magnesium to the iron. When alloying with pure magnesium, use

where one enters "different" irjection methods, where magHii^iim in powder or grain form with the help of a carrier gas blows sp;s^-|iti into the iron in an open .vessel~..or then -larmoon-fixed magnesium in\Aatb4re pieces react with it molten iron in a hermetically sealed vessel, where rapid rpressure;,.vby:gges..,ppp,,,,.; V^ed application of magnesium-r alloys kaji. d;4ssse^^anbj:ipge,s. they have higher density than the molten iron, are thrown into the molten iron.

Alloys lighter than iron are often introduced with oozes that are submerged or similar. Since, at the iron temperatures at which the magnesia is heated, the vapor pressure is very high, the reactions will be very powerful. s because the magnesium alloys melt and • 'forget^egSi^huf; <iJii>° whereby a large; amount of magnesium gas is evolved in a very short time;

A kifaftig^ltbk^f åis, dåciegér'ihgen?bftest;'skjer - in: -open vessels,

some iron is usually thrown out of the reaction vessel and a strong flame burning magnesium gas is produced "by the magnesium •'■ which::i"i;J does not have time to dissolve in the iron*;;. The yield, calculated as the amount of magnesium in nodular iron in relation to the added amount of magnesium, is very low and rarely exceeds 0.5 (20 - 50%). The disadvantages of the methods used so far can be summarized as follows:

1. Alloy with NiMg (15% Mg).

This is a very expensive method as the Ni metal is expensive and also troublesome flames occur and poor yield

2. ^c:llÆgeranglmed-:FeSiMg;••(•5.- -:;20;# MgH?-] ' ''■■ n. sd^- i ^This is one': method with very difficult flames; ' risk -ioFutk^stning of iron and: f or'low'yield

3a. Injection methods.

ins. nm. pse metp.dérspppvåser^megetf héf.tige:.f lammerJ; :. risl-korf orv-V

^aa^a^nåiig:>.a&!.«meJ.tei^tj.ermÆra the mixing vessel>i.storehtempe--pii - xsX fjjaj^rfcapaiogafflegete low u*by£te>6- r~ s* hg^ i: :> ayifi»tjte>:>a r;& m 3b Tr^kkåmiie^rmeil^oaer :J",!>!i;Xf;-f'v';:n <>p ^ riX <i>,^< bn;>>.<ø>

These methods require complicated and expensive apparatus with vessels, " tUl' r<ii>vificé hbye" tf yklt'^opps tor and give "for certain .mefcodes ..large temperature loss and low yield. r, „

s%æ"rværeitcié oppr"inhélse'"reHusVrér' the disadvantages mentioned above. jThis . directs itself IsaieBés^^on<*> one" miscible intended for processing molten iron which is cheap and gives a high yield and. small temperatures -,.;

few losses at the same time as it does not require any complicated or expensive equipment for its application. mechanical mixture of powdered or chip-shaped magnesium, which serves as an alloying agent, and iron sponge, which serves as a reaction delaying agent and the magnesium constitutes 4-40% preferably 5-25% of the weight of the solid bodies. Véd'*<5>the production magnesium powder is mixed mechanically with crushed iron sponge, after which the mixture is formed into solid bodies. The mixture can be briquettes; Denikån can also be combined with appropriate binders to form the solid bodies. The briquettes can, for example, have cylindrical ' form, the diameter of which must be 120 mm and the height can be 100 -

150 mm, i.e. <the solid bodies have a volume of the order of one dm^. -^i'^'^''"^ -~;"' -'■ ;' -<;>'-••.-•'•■'<;:> :-; - '•''*' ■'''■

The amount of magnesium in the solid bodies can vary within wide limits with regard to the amount of magnesium in the body. 7 Thus the magnesium can make up 4 -':i40 % :aV :'dé:! solid' ié^emérs^weight^"and preferably it constitutes 5 - 25% of the weight of the solid bodies.'; ;

It is about making the magnesium that serves as an alloying agent melt and gasify relatively slowly, so that the magnesium gas. •. „ A in a relatively slow strbm passes through removed. This gives less flames and a faster yield?! - For.i.mentioned'; purpose [is - Aa- icM the bodies pprbse,.so that r,all ..after,. as:.. the temperature" rises in these; the magnesium gas formed is pressed out and alloyed with the iron. Appropriate porosity is achieved if the solid bodies are given a mass density of between 2 and 4 g/cm, the lower volume density being a mixture with a high amount of magnesium, and the higher volume density applies to a mixture with a low amount of magnesium. Normally, the mass density should be around 3 g/cm3. For comparison, it can be mentioned that the density for compact iron sponge is around 7 g/cm3, which is why the bodies have a porbsite of about 50%.

In certain cases, smaller amounts of other substances can also be included in the mechanical mixture compressed into solid bodies. Thus, either cerium, mixed metal, etc. or ferrosilicon, graphite, slag binders and the like are included in the mixture, whereby the amount of the additive would normally amount to approx. 0.5%.

In the production of nodular iron, the solid bodies can be fed down with the help of an immersion die or the like into a pig iron melt adapted for the purpose in a treatment vessel whereby the inclusion of magnesium is achieved.

Claims (3)

1. Briquettes intended for the introduction of magnesium into molten iron, characterized by the fact that they consist of a mechanically compressed mixture of magnesium in chip or powder form, which serves as a treatment agent, and crushed sponge iron, which serves as a reaction delaying agent, compressed into solid porous bodies, as the magnesium constitutes 4 - 40%, preferably 5 - 25%, of the weight of the solid bodies. 2. Briquettes according to claim 1, characterized in that the solid bodies have a mass density of 2 - 4, preferably approx. 3 g/cm"*.