To appreciate the value of our local iron industry, we should consider that iron when melted into pigs contains other ingredients than pure iron, some of which add to its values if found in reasonable quantities, and there are other ingredients that detract from the value if they exist in any great amount. Manganese adds immensely to the value of the metal, increasing its strength and tenacity. Slight traces of manganese in the lime used went into the iron during the melting process. Carbon increases the strength of the iron and closes the grain, making the metal difficult to work if found above 3%.
Higher content of the carbon makes the metal suitable for steel if the pigs of iron are remelted and treated in a puddling furnace or by modern Bessemer furnaces, wherein “Spiegeleisen,” a rich iron found in Norway and Sweden, is often added to produce high grade of steel. Wrought iron and steel from this process is forged into shapes suitable for building and other domestic purposes for which pig iron is unsuitable. Pig iron with low carbon is known as “white iron.”
Silicon softens the iron making it suitable for general foundry purposes but should not exceed 2-1/2 to 3%. Sulphur and phosphorous in excess of 1% lowers the value of cast iron through brittleness in castings made from it. Kent iron was free from excess of any of these ingredients and could be used to build up a mixture with iron of lower grade or with heavy scrap iron, and its judicious use in this maneuver would produce any grade of casting required, giving a wide range of strength and tenacity as its use might indicate. Kent iron was graded No. 1, very soft, to No. 6, very hard, and only suitable for producing great strength in casting made from it.
Kent Ore Mine was dug into the side of a mountain east of the highway which runs from South Kent over the mountain to the “Cobble.” Entrance to the mine was kept on a level or slight upgrade from the highway into the hill until an excavation was made 600 feet to 800 feet in diameter and 150 feet high against the hill. These seams of iron ran out about 1850 and a deep shaft was dug with galleries led off and worked as iron was found. There were several levels opened and worked with radial galleries in all directions from the shaft. All ore and much of the refuse had to be hoisted to the top of the shaft, and pumps were kept running to free the mine of water which continually seeped through the ground.
At its best this mine turned out 15 to 20 tons of ore per day and this was carted to the furnace six miles via South Kent. Teams went over the mountain to the mine as that route was a third shorter, but the grade most of the way was at least 30%. Ten to twelve teams were then employed making two trips per day, leaving the furnace barn by 6:00 a.m. and returning at 6:00 p.m., bringing in about 1-1/2 tons of ore per trip. On arrival at the “bank” each load was weighed and dumped near the furnace. Large chunks of ore were separated from small pieces and in the early days were broken up with sledge and hand power. In later years a crusher was used for breaking up ore and lime.
With the advent of the railroad, with a switch to the furnace, other ores were brought in from Salisbury, Connecticut, Amenia, New York and Richmond, N.Y., the latter being close to the terminal of the Housatonic Railroad at State line. These ores probably cost Kent Iron Company less than their own ore from Kent ore bed, but the mixture employed produced first class iron.
The stack in which the ore was melted was approximately 25 feet high from its bottom and where the melted iron was drawn off to the charging floor where charcoal, lime and ore were dumped in at about half hourly intervals or less. This necessitated building the stack on a side hill affording two levels, the lower for the casting house which covered about 100 feet by 250 feet and the upper level for a charging floor of about the same area, but the upper level led out to the “bank” and covered about two acres of ground. All materials for the furnace came to the “bank” for immediate use or temporary disposition.
There were six to eight loosely built structures for housing charcoal for storage against weather and they were usually filled during the summer weather as little or no wood used was “coaled” during the winter, during which season the wood for coal must be cut while free from sap.
The stack was approximately six feet in diameter at the bottom and four feet at the charging floor. “Haswell” tells us that 138 bushels of charcoal, 432 lbs. of lime and 2612 lbs. of ore melted in the stack should produce a ton of iron, but this depends somewhat on the quality of the ore, lime and charcoal use, also on the blast of air supplied to maintain perfect combustion. “Haswell” again says that for a stack of our capacity, 14 tons per day, approximately 5200 cubic feet of air should be supplied per minute at about 5 to 6 inches of mercury pressure.
Coal, lime and ore were loaded into special two wheel dump carts in the top house each holding the proper amount for a charge, and were dumped into the stack as previous charges settled down. Charcoal carts held about forty bushels, and ore and lime carts in a proportion of 125 lbs. of lime and 750 lbs. of ore, charges being made half hourly. The bottom of the stack and immediate sides were lined with heavy granite blocks of stone on which melted iron accumulated for six to eight hours at a time, at which intervals the iron was drawn off through an opening above the “hearth” temporarily stopped with fire clay baked in.
The “tapping” was done with a long iron bar and the iron ran out through a trough in the dirt floor to a bed formed out of a fine grade of sand found in places along the river. This bed was made with long strips of wood extending from the furnace to the end of the casting house, tamped firmly in sand moistened to hold their shape and then removed.
This long strip was called the “sow” and lateral branches about 3 feet long were taken off the side of the “sow” and for obvious reasons were called pigs. As soon as the iron cooled sufficiently the sows and pigs were broken up into short lengths pulled out on the casting house floor and carted out in ox teams to be piled along the railroad ready to ship, carefully sorting and making each grade by itself. A by-product of no value was produced in melting the iron and this was known as “slag” which floated above the iron in the stack, being much lighter, and its flow was constant, running out from the stack onto the casting house floor where it cooled rapidly, was broken up and carted out to be dumped on waste piles about the furnace.