Method for the determination of hydrogen content in inorganic materials

A sample of an inorganic material is placed into a hermetically sealed electrode pulse furnace and heating and melting of the sample are effected at a temperature within the range of from 1,600.degree. to 2,500.degree. C. Delivering of the hydrogen evolved upon melting from the unsealed furnace to the site of its quantitative recording is effected by means of an inert gas at a temperature of from 1,600.degree. to 2,500.degree. C., which makes it possible to determine the content of hydrogen with an accuracy of 2.times.10.sup.-3 % by mass in inorganic materials, for example slags, within a period of from 5 to 10 minutes.

The present invention relates to metallurgy and, more particularly, to a 
method for the determination of hydrogen content in inorganic materials 
such as slags resulting from metallurgic processes. 
FIELD OF THE INVENTION 
The method according to the present invention is useful in steel-melting, 
blast-furnace processes for the determination of conditions of said 
processes. Furthermore, the method of the present invention can be used in 
non-ferrous metallurgy. 
BACKGROUND OF THE INVENTION 
Known in the art is a chemical method for the determination of hydrogen 
content, for example, in blast-furnace slag, which is based on 
determination of the amount of carbon dioxide produced upon reduction of 
water contained in the slags according to the following reactions: 
EQU 2H.sub.2 O+2C=2CO+2H.sub.2 
EQU 2H.sub.2 +2CuO=2H.sub.2 O+2Cu 
EQU 2H.sub.2 O+CaC.sub.2 =Ca(OH).sub.2 +C.sub.2 H.sub.2 
EQU C.sub.2 H.sub.2 +5CuO=2CO.sub.2 +H.sub.2 O+5Cu. 
However, this is not a versatile method, since it is suitable only for 
blast-furnace slags, is labour-consuming and takes a long time of from 4 
to 6 hours. The greatest difficulties are encountered in the determination 
of hydrogen content in fluorine-containing slags, wherefrom from which 
hydrogen can be evolved upon heating in the form of H.sub.2, H.sub.2 O and 
HF. In order to avoid losses, the total combined hydrogen content should 
be converted to free hydrogen. Very complicated transformations are used 
for analysis of fluorine-containing slags in a current of oxygen at the 
temperature of 1,200.degree. C. which, apart from complicating the 
analytical procedure, cause possible errors. 
Also known in the art is a method for the determination of hydrogen in 
oxide melts which involves melting a sample at the temperature of 
1,600.degree. C. in an inert gas current. The water liberated from the 
slag and carried-off by the gas current is passed to, for example, a 
quartz pipe filled with ferromolybdenum, wherein it is reduced to hydrogen 
and carbon dioxide. The amount of hydrogen is determined by one of the 
conventional methods such as by chromatography. This method is rather 
complicated and labour-consuming and takes about 1-2 hours for the 
determination. 
Another known method for the determination of hydrogen content in metals 
involves melting of a metal sample in a graphite crucible placed into an 
electrode pulse furnace at a temperature within the range from 
1,800.degree. to 3,000.degree. C. Melting of the metal sample is effected 
in a current of a carrier gas intended for delivering the evolved hydrogen 
to the site of its quantitative recording, for example a thermal 
conductivity sensor. 
In the use of this method for the determination of hydrogen amount in slags 
(due to the fact that hydrogen in slags is in the form of water) there 
occurs an incomplete reduction of water to hydrogen due to a continuous 
removal of water vapours from the reaction zone and, consequently, lowered 
results are obtained in the determination of hydrogen. 
It is an object of the present invention to overcome the above-mentioned 
disadvantages. 
It is an object of the present invention to provide such a method for the 
determination of hydrogen content which makes it possible to determine the 
amount of hydrogen in inorganic materials, for example slags, with maximum 
possible accuracy. 
It is another object of the present invention to provide such a method 
which makes it possible to determine the amount of hydrogen in inorganic 
materials, for example slags, within the shortest possible time and at 
minimum possible labour expenses. 
BRIEF SUMMARY OF THE INVENTION 
These objects are accomplished in the determination of hydrogen content in 
inorganic materials by the method involving melting of a sample in a 
furnace in a graphite crucible at a temperature within the range of from 
1,600.degree. to 2,500.degree. C. in an inert gas atmosphere and delivery 
of the hydrogen evolved upon melting in a current of an inert gas to the 
site of its quantitative recording, wherein, in accordance with the 
present invention said melting of the sample is effected in a hermetically 
sealed furance during the period of time sufficient for complete removal 
of hydrogen-compounds from the sample, whereafter the hydrogen evolved is 
discharged from the furnace at the above-specified temperature. 
The method according to the present invention makes it possible to 
determine, within the period of from 5 to 10 minutes, the amount of 
hydrogen with an accuracy of 2.times.10.sup.-3 % by mass in inorganic 
materials, for example in slags. Furthermore, the method according to the 
present invention can be readily automated. 
Further objects and advantages of the present invention will now become 
more fully apparent from the following detailed description of the method 
for the determination of hydrogen content in inorganic materials and 
Examples illustrating its embodiments. 
DETAILED DESCRIPTION OF THE INVENTION 
The method according to the present invention is suitable for the 
determination of the amount of hydrogen in slags (resulting from 
blast-furnace processes, steel-making) fluxes, crystalhydrates and other 
inorganic materials containing hydrogen in both free form and as water. 
To practise the method of the present invention use is made of e.g. 
electrode pulse or induction furnaces of conventional arrangement having a 
graphite crucible. 
The sample to be analyzed, for example slag, is placed into a graphite 
crucible preliminary outgassed at a temperature of 2,000.degree. to 
3,000.degree. C. in a current of an inert gas. Thereafter, the crucible 
with the sample is repeatedly purged with an inert gas for 5 to 10 
seconds. 
In accordance with the present invention, prior to melting of the test 
sample the working space of the furnace should be hermetically sealed in 
order to provide conditions for a more complete proceeding of the reaction 
of reducing water to hydrogen. The temperature at which water contained in 
the sample is reduced to hydrogen is within the range of from 
1,600.degree. to 2,500.degree. C. depending on the nature of the analyzed 
material; for example, in the determination of the amount of hydrogen in 
borax Na.sub.2 O.sub.2 B.sub.2 O.sub.3.10H.sub.2 O the process temperature 
is varied within the range of from 2,200.degree. to 2,400.degree. C. 
It has been found that for a complete progress of the process 3 to 15 
seconds are sufficient, (however this time may vary depending on the kind 
of material) i.e. within this period complete removal of the 
hydrogen-containing compounds from the sample occurs. Then the furnace, 
without discontinuing the heating thereof, is unsealed and the evolved 
hydrogen is delivered to an analyzer such as a chromatograph by means of 
an inert carrier gas, for example argon. Due to the fact that the evolved 
hydrogen is withdrawn from the furance without interrupting the heating 
thereof, i.e. at a temperature of 1,600.degree. to 2,500.degree. C., it 
has become possible to attain a more complete reduction of the water 
vapours that evolved from the sample being analyzed and are found in the 
reaction zone (on the walls of the reaction vessel and within the pores of 
the furnace members). 
The present method makes it possible to determine the hydrogen content in 
the analyzed inorganic material with an accuracy to 2.10.sup.-3 mass %.

EXAMPLE 
Hydrogen content is determined in a sample of borax Na.sub.2 O.sub.2 
B.sub.2 O.sub.3.10H.sub.2 O on a unit with pulse heating and a 
chromatograph. 
A sample weighing 0.02 g is placed into a charging device and a graphite 
crucible with a batch of tin (0.05 g) is placed into a furnace. Tin serves 
to preclude the absorption of hydrogen by graphite sublimates. 
The graphite crucible is degassed at a temperature of 3.000.degree. C. by 
passing a current pulse for 6 seconds and purging the furnace volume with 
purified argon to remove the gases to the atmosphere. Then the furnace 
heating is switched off, the borax sample by means of the charging device 
is transferred to the graphite crucible, the furnace is purged with argon 
for 10 seconds, then the furnace volume is sealed, heating thereof is 
switched on, and melting of a sample is effected at the temperature of 
2,300.degree. C. for 4 seconds. Then, without switching off the furnace 
heating, the furnace is unsealed, and the reaction product is transferred 
to the chromatograph through the agency of a stream of argon. 
The results of the determination of the amount of hydrogen in borax 
obtained by the method according to the present invention and by the prior 
art method are shown in the following Table. 
TABLE 
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Tem- 
pera- Number of Amount of the 
ture, determina- 
evolved hydro- 
Method of analysis 
.degree.C. 
tions gen, % 
1 2 3 4 
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Purging of the furnace 
working space with an 
inert gas during melting 
of the sample 2,300 20 55 .+-. 18 
With sealing of the fur- 
nace working space during 
heating and melting of the 
sample 2,300 20 96 .+-. 8 
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Therefore, the method according to the present invention makes it possible 
to perform determination of the content of hydrogen in inorganic materials 
with high accuracy and sensitivity. 
The application of the method according to the present invention in, for 
example, the metallurgical industry will make it possible to obtain 
reliable data on the content of hydrogen in slags which is one of the most 
important preconditions of the production of a high-quality metal.