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The blast furnace at Toplita, Hunedoara

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1 The blast furnace at Toplita, Hunedoara la data de 19.04.10 0:24


By Dr eng. Romulus loan


The presence of important reserves of iron ore at Ghelar and Teliuc,Transylvania - in present day Romania - as well as plentiful forests forcharcoal and a tradition in processing iron,
resulted in a blast furnace being built at Toplita, in the Cerna Valley, some 15km upstream of the Hunedoara Estate. The documents of the time do not mention this early blast furnace. It is possible that the furnace started operation before 1754 since the Urbarium of that year men-
tioned that a forge with four hearths, referred to as ‘New Shop’ (Baia Noua), had been built near the 'high furnace' (blast furnace). This was the first forge in the region to make wrought iron from pig iron. Since forges using pig and bloomery iron werealready operating in the Cerna Valley it is hard to imagine that the pig iron was brought from other regions since it was a long distance to the nearest blast furnace, at Banal.
The first document that presents precise data about the Toplita blast furnace dates from 1787, and records that during that year the furnace was operating with 112 double shifts of 12 hours each. During that time, 27826 Viennese majas and 88 fonts (1563.9t) of ore were processed, out of which 9431 majas (528t) of pig iron resulted. The yield was 33.75 fonts (18.9kg) of pig iron from one majas of ore, and the average daily production was 84 majas and 33 fonts (4.72t).That
year the blast furnace was stopped and repaired twice because of wear of the hearth. On the 4th of October 1780 four workers from Hunedoara were sent to Styria in Austria for training in new working practices. Zaharia Pascu, the furnace man, was among them.
In the spring of 1780 the administrators of the Hunedoara estate undertook a series of measures to construction (or rebuild) a blast furnace. The documents mention that on March 1st 1780, 20000 tiles of wood (forcovering the shop) were bought and tools for the construction works were prepared.Preparations began on March 15th 1780, 130 workers preparing the site where the blast furnace was to be built. A great
amount of wood was necessary for its construction. Later in March, another 200 workers were hired, but the snow that still covered the mountains prevented them from cutting and stacking the wood. For transportation of planks, tiles and stones,1658 florins were paid.
Once the site was ready, the administrators began looking for a specialist to build the blast furnace (Flossofen), the appointment of which was indispensable for starting construction. Negotiations with an ironmas Toplita blastfurnace, Romania 1781ter called Ediinger, living in Styria, Austria, resulted in his appointment. Zaharia Pascu, the furnace man sent for training, also returned, the two arriving on March the 31st 1781. The Styrian master was satisfied with
the location of the furnace and the quality of the works. Ediinger used local stone to build the furnace shell and made the hearth out of clay. Unfortunately, Ediinger fell ill and on June the 21st 1781, died. Construction work continued under thesupervision of the estate administrator, Mr Matsch and Zaharia Pascu, with Pascu effectively controlling the whole process. The fur-
nace was put into operation on July 13th 1781.
Toplita blastfurnace, Romania 1781
The blast furnace was faced entirely with cut stone. The main technical characteristics and dimensions of the furnace, recorded inhistoric documents, were:
- Working volume: 6.94m3
- Total height: 21 feet (6.64m),
- Hearth diameter at bottom: 2 feet and 4 inches (0.735m)
- Bosh diameter: 5 feet (1.58m)
- Height of the bosh above hearth (upper bosh line at): 2.42m
- Throat diameter: 2 feet (0.632m),
-Height up to the first tuyere: 18 inches (0.479m),
- Height up too the second tuyere: 36 inche (0.948m).
- Height up to which annual repair work was done: 60 inches (1.58m),
- Charcoal consumption: about 1905 kg/t hot metal.
The hearth was a little inclined towards the tapping hole so that discharging of the liquid metal and slag was easier. Each of the two tuyeres was fed with air from a pair of leather bellows driven by a water wheel with buckets 4 feet (1.264m) wide and of radius 3 feet and 3 inches
(1.057m). The bellows could each give 6 to 7 blasts a minute but when the flow rate of theriver Cerna dropped, especially during hot summers, they gave only 4 to 5 blasts a minute. Within a few years, to satisfy the ever increasing demand of pig iron, theChamber from Vienna asked the Hunedoara estate to increase the height of the furnace, a practice already used in other countries. This was completed in the spring of 1805. The new working volume of the furnacewas of 10.91m3, according to a document dated 1830, and its main dimensions were:
- Total height: 21 feet and 6 inches (6.79m)
- Hearth diameter at the bottom: 34 inches (0.946m).
- Bosh diameter: 65 inches (1.817m)
- Height up to the first tuyere: 18 inches (0.479m)
- Height up to the second tuyere: 20 inches(0.526m),
- Throat diameter: 34 inches (0.946m).
The furnace was charged with ores from local mines and pits, iron recovered from the slag and other additions. The charcoal was made from beech wood. Charcoal from the neighbouring region of Valea Jiului was introduced in 1770, but this reduced results since it was poor quality and its transport also incurred high costs. On December 9th 1836, the Treasury Office from Transylvania ordered an investigation to establish why the charcoal used in the blast furnace and in the refining furnaces was of bad quality. The poor quality of iron ore and charcoal as well
as insufficient knowledge of the refining process were the cause of much waste. In 1836, the administration of the Toplita blast furnace admitted that only poor quality iron bars were produced out of the pig iron obtained from the ore used. The same year, the Hunedoara estate presented a clear report on the poor yields from the blast furnace, iron shops and warehouses. It listed the causes leading to the waste and gave possible remedies. In the documents they mentioned that much of the poor yield was a result of attempting to obtain the highest output of white pig iron possible (as opposed to grey) and the consequential tapping temperature of the iron.
The administration of the estate carried out research to discover a better lining for the furnace using stone in the neighbourhood of Toplita.
Output from the blast furnace was maintained at a constant level for much of the time. A document of 1799 mentioned a weekly production of 604 to 692 majas (33.8 - 38.8t) at a yield of 37.25 - 40.50%. The pig iron to be refined was poured into blocks. Usually the blast furnace produced white pig iron for refining, but also grey cast iron and grey spiegel iron were made when needed. Thus, between 1801 - 1802, 90% of the pig iron was white, 7.5% was grey and 2.5% grey spiegel iron.
From 1808, the blast furnace also started producing items cast directly from the furnace. Demand increased and rose to 50t/y.Total production at this time showed larg variations from one year to another, depending on market possibilities and the repair works needed. Thus, 528t were produced in 1787, 1400t in 1802 and a peak output of 2460t was recorded in 1836. Very low outputs were obtained in 1794 (187.5t) and 1813 (23.8t), years when general overhauls were
carried out on the furnace
The Toplita furnace ceased operating in 1837 as a result of a fire that broke out on the night of 15-16th of January that totally destroyed the building, the installations andthe materials in the warehouses.

Evolutia furnalelor de la Toplita pana la furnalul nr.9:

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