SE451949B - PROCEDURE FOR THE PREPARATION OF CURRENTS - Google Patents

Description

451 949 2 The problem according to the invention is to develop a process for the production of high-bulk carburizing agents density, which compared to comparable carburizing agents increased dissolution rate in steel and iron melts.

The problem is solved according to the invention by a preparation carbonation process by compacting carbon powder with binder in that, in order to increase the body density the mixture is added with a component with high density with a grain diameter less than 2 mm.

Metal powder can be used as a component with high density of the alloying components of the steel to be produced in each particular fail such as e.g. Fe, cr, Ni, w, co, Mo, Mn, V or Cu alone or as a mixture. It is also possible it is possible to use metal chips such as e.g. gray cast iron or non-slag-forming additives such as e.g. ferromanganese and ferrous silicon.

As carbon powder, the powders of all common carbonators, which, in addition to a high carbon content, contain only small amounts of harmful excipients such as sulfur, hydrogen, nitrogen and ash. Particularly advantageous, however, are time powder of carbon material with a pronounced graphite-like structure such as premium coke or electrographite.

Compaction can take place by extrusion, briquetting pelletization, to which, depending on the binding means a drying or calcination of the shaped bodies must adhere, in order to the content of volatile constituents or hydrogen should be reduced. The binder must not increase the proportion harmful accompanying elements in the carburizing agent.

According to a special embodiment of the process is mixed graphite powder with a grain diameter 5 2 mm with k0mP0 fl either with high density in the ratio 1:10 to 10: 1 during addition of 1% hydroxyethylcellulose in the dry state and mix with 10-25% water depending on the fineness of the components of solid material and less than 1% of a base of an alkali metal or alkaline earth metal or ammonia water, based on it dry the mixture. This nassa is then compacted on i and known method for 3 to 15 mm large compacts, which then dried for 5 to 20 hours at 80 to 180 ° C. ä. .S7 s 451 949 In the following examples, the invention will be explained in more detail without thereby being restricted.

Example 1 129 parts by weight of turf shavings with grain sizes below 2 mm mix dry with 69 parts by weight of graphite powder with grain sizes between 0 and 2 mm (analysis in Table 1) and 2 parts by weight of hydroxy ethylcellulose for 5 min. After adding 40 parts by weight water, the mass is homogenized for another 5 minutes. Then add 0.06% by weight of 10% strength sodium hydroxide solution is added. After another 2 min mixing time, the finished mass is processed in an extruder with a 35 mm strong die, which has cylindrical bores 5 mm diameter, into compacts, which are then dried to a residual humidity of less than 0.5%. The dry compact the pairs have a bulk density of 1600 kg / m ”and a carbon content of 37 weight-%.

Example 2 According to Example 1, compacts are prepared from 69 parts by weight gray castings and 129 parts by weight of graphite powder. The dried presses the bodies have a bulk density of 1100 kg / ma and a carbon content of 70% by weight.

Of the carburizing agents listed in Table II were determined under comparable conditions, the carbon absorbed by the steel melt the amount as a measure of the dissolution rate. The experiments were carried out was placed in a 5 ton induction furnace. In each case, separate case the same amount of coal of 30 kg. The sampling took place each time after 5, 10 and 15 min. The total quantity carried the amount of carbon absorbed by the melt (carbon yield) is shown in diagrams.

As can be seen from the diagram, the dissolution rate is for the carburizing agents prepared according to the invention as well even their carbon yield after 15 min higher ä at best known carburizing agent graphite. 451 9119 4 Table I Analysis of the fine-grained graphite Carbon content 99.2% water content 0.013% nitrogen content 0.05% sulfur content 0.02% volatile 0.57% ash - 0.15% humidity 0.2% The percentages refer to% by weight.

Table II Carburizing agent Grain size [mm] A1 (according to Example 1) A2 (according to Example 2) graphite petroleum coke beckkoks U1U1U1 Bulk density [kg / m ”] 1600 1100 800 soo 450 Coal content [weight-%] 37 70 99 97 98 100 ' 90- 80- 70- 60 ~ 50- A0 ' 30- 20- 10 ' 451 949 Chart Carbon uptake of various carburizing agents w / .,., / // ä * - / / b. / 3 / m 9-1 E. å + A1 X A2 O Gra_fit .IN Ü Petroleum coke _ A Beckkoks ------- c- Reaction time [min] IN 10 15

Claims (1)

Process for the production of carburizing agents with increased dissolution rate by compacting carbon powder with a binder) characterized in that graphite powder having a maximum grain diameter of 2 mm is dry-mixed with pure metal powders of the steel alloy components, finely divided metal chips such as, for example, gray ingot and / or powder of alloys of the heavy additives customary in iron and steel production, such as ferro-manganese and ferro-silicon in the ratio 1:10 to 10: 1 with the addition of 1% hydroxy ethylcellulose, mixed with 10-25% water and less than 1% of a base of an alkali or alkaline earth metal or ammonia water, based on the dry mixture, and then compacted in a manner known per se to 3 to 15 mm large: shaped bodies, which are then dried at 80 to 180 ° C for 5 to 20 hours