Liquor.

The liquor recovered by the carbonisation of lignite contains an appreciable quantity of ammonia, but it is unlikely that this would ever repay recovery. Normally, lignite has a high moisture content and, when carbonised, large quantities of water are liberated in the early stages. For this reason the ammonia concentration is much too low for efficient recovery. With the samples under investigation the average yield of liquor amounted to 68.7 gallons per ton of lignite as charged. The percentage of ammonia in this liquor was about 0-27, or only one sixth of that which, at the present time, is regarded as strong enough to justify recovery. If the lignite were charged dry the yield would have been 29 gallons at a strength of 0.64 per cent NH3, which would also be too low for recovery. The analysis of the liquor collected from each lignite is shown in Table 5.

Tar.

As already stated, the yields of tar were very disappointing. Shortage of lignite prevented the carrying out of repeat tests as would otherwise have certainly been done.

The reasons for the low yields have already been surmised on page 372 but definite conclusions do not appear possible.

The actual yields calculated as gallons per ton of dry lignite are shown below in comparison with those of the laboratory experiments. Experience with the laboratory apparatus has shown that a bituminous coal will yield 66 per cent more tar in it than in the experimental horizontal retort. If this same factor were assumed for lignite, which is not unreasonable, the results obtained should have been as shown in the second column.

Tar yields in gallons per ton of dry lignite.

From this it is apparent that only half of the predicted yield was realised.

In spite of this discrepancy it was decided to carry out a certain amount of examination of the tar.

The samples as collected were in all cases very similar in appearance, being brownish black, semi-solid and having an unpleasant smell. When cold they set to an almost black solid of a waxy appearance which seemed to contain soft crystals. When warmed they became quite fluid at 30° C.

The examination of the tar was only possible on the mixed samples, owing to the small amount recovered in the other cases.

A preliminary distillation was carried out and the resulting fractions were examined separately by washing with sulphuric acid and caustic soda for basic and acid bodies. The refined oils were then distilled and the tar acids separated, washed, and fractionated.

The results of this examination are shown in Tables 6, 7, 8 and 9. These give some idea of the nature of this lignite tar. More elaborate examination was not attempted owing to the doubt which attached to the yields and the fact that the unsatisfactory collection of the samples may have resulted to some extent in an alteration of the distribution of the various products in the tar.

"Montan Wax".

The percentage of montan wax in the Namma lignite was determined and found to be approximately two per cent on the dry lignite. It is doubtful whether so small a yield would justify recovery, but this would depend largely on local conditions and supplies of other waxes.

SUMMARY.

Five samples of Burmese lignite from the Superintendent of the Geological Survey of India were examined at the Fuel Re. search Station.

These samples represented three different coal fields, there being three separate samples from one field.

(1) Namma Coal Field, N. Shan States.

(2) Lashio

Pauk

(3) Yekkyin stream.

(4) Thongwa stream.

(5) Newè stream.

All five samples were fully examined in the laboratory and the results are given in Part I of this report.

The investigation was completed by the carbonisation of samples of about 100 lbs. each in a steel horizontal retort. In this case samples (3) and (4) were treated together as a mixture, as their properties were very similar.

The results of the carbonisations are discussed in this report and the full examination of the products is also shown.

The yields of tar actually obtained were very low and the examination must be considered as unsatisfactory in this respect. It seems probable that the whole of the tar was not collected, but the amount of lignite available was insufficient for repeat experiments. The nature of the average tar as collected has been investigated to some extent and the results given.

The other products gave more satisfactory yields.

When the dry lignite is considered as a basis no great differences exist in the yields obtainable by a carbonisation process. These yields are most readily compared by consulting Table 2 and may be summarised as follows:

The Namma and Lashio deposits give average yields of volatile therms, (gas and tar) while the Pauk deposits are richer in the Yekkyin and Thongwa streams and poorer in the Newè stream.

It is not possible to draw full and definite conclusions from the examination of Burmese lignites which were carried out at H. M. Fuel Research Station, East Greenwich, owing to the limited samples available. The following tentative remarks, however, may be of assistance to those who are commercially interested in the development of the natural fuel resources of the country. 1 де sample from the Namma field consisted of fairly large pieces and the strength of these and the absence of partings seemed to indicate,

m

D

that this lignite was strong enough to stand handling, and that as mined, the percentage of fines or slack would not be excessive. The sample from the Lashio field was brittle and the larger pieces contained partings which gave them a tendency to ready disintegration. The samples from the Pauk coalfields were also brittle and contained a high proportion of fines.

So far, therefore, as it is possible to draw conclusions from the small samples under examination it would appear that for direct use as a fuel the most satisfactory would be Namma lignite and that the others would tend to contain, after handling and transport, a high proportion of slack or dust.

The calorific values of the lignite as mined varied from 5,500 to 7,800 B. Th. U's per lb. or from 9,040 to 10,880 B. Th. U's per lb. on the ash-free dry fuel.

*

If the lignites were subjected to a process of carbonisation the chief problem would be the supply of heat to the settings and the suitability of the resulting coke. The heat available in the form of gas amounts to only 15 to 21 therms per ton of lignite and of this approximately 5 therms would be required for the removal of the moisture alone. It is doubtful, but just possible, that a system could be devised in which the gas made would be sufficient to carry on the process. The tar yielded would vary from 5 to 10 gallons (60 per cent of the "assay" yield) per ton of lignite and would serve as a source of fuel oil.

The coke produced would vary considerably. From a strong lignite such as Namma the pieces would probably remain approximately in the shapes and sizes charged, but would be friable owing to the presence of innumerable cracks. With the more brittle and dusty lignites it does not seem possible that the coke could have any application as a sized fuel. On the other hand, however, it would seem to be a favourable material for use as a pulverised fuel.

It is possible that a robust fuel might be obtained by subjecting the material to some process of briquetting followed by carbonisation. This briquetting might take the form of compression without added binder or of briquetting with a suitable binder could one be obtained locally. On the laboratory scale the material yields good briquettes with pressure alone and little disintegra00,000 B. Th. U.

* 1 therm

not

tion is apparent during subsequent carbonisation. It does follow, however, that the fuel would not disintegrate during carbonisation when the processes are on the full scale. If such a process proved possible the resultant fuel would possess properties such as higher calorific value and would be more suitable to withstand transport than the raw lignite. This however could only be proved by work on the large scale.

TABLE 1.-Results of carbonisation of 100 lbs. lignite at 600°C.

TABLE 2.-Yields per ton of dry lignite in comparison with laboratory