Section IV : Jig Box etc.

Treatise on Coke Page 115

In Fig. 34, a is the unwashed-coal storage bin, of any size that may be desired, holding the coal of all sizes, as the coal is not screened or sized prior to washing. b is a sliding cast-iron gate, operated by rope or lever, that admits the coal from a through c into d. c is a sheet-iron housing fastened to the jig box d and extending into the box. This is to force all coal going through c under the water-line, so as to prevent any fine dust from floating on top of the water and passing out over the end of the jig without its having become subjected to the action of the water. d is a jig box, about 5 feet X 7 feet, that is fitted into the jig tank e by metal plates on the four sides of jig tank and on jig. This jig box has a reciprocating movement and is worked by double eccentrics f and g keyed to shafting, lying parallel and geared into each other to run at the same speed. The jig box is hung from f, g by eight rods h. The coal after passing through c is at once immersed and goes through a complete disturbance from eight to ten times before it reaches the point of discharge for the coal j and for the slate k. The box has, in the bottom, perforated plates that slope to the front end where there is a sliding gate l. The capacity of the jig is 20 to 40 tons of coal per hour. The jig tank e is built in size to suit the jig box so as to allow it to swing free. The tank is bushed in on four sides with iron plates to fit squarely against the same character of plates on the jig box, giving the result of a practically tight joint, but at the same time giving the jig sufficient play so that it can be moved up and down by the eccentrics f and g hung on the two pieces of shafting just over the jig. As the jig box goes down, the water is forced through the perforations in the plates with sufficient force to carry the coal of a certain specific gravity up and over the lower end of the jig, the water being sluiced through an open trough to the settling tank or basin o; the speed of the jig depends entirely on the specific gravity of the coal that is being worked.

The slate gate or refuse discharge l is raised and lowered at will by the lever m. The opening at k is adequate to pass a 4-inch cube, and is the entire width of the jig; the lever m is fitted to a radius of a half circle with slot to accommodate the opening and shutting of the gate l, and is fitted with handscrew so as to enable the setting of this gate at any height. The operator of the jig, after becoming familiar with his coal and the amount of impurities it carries to the ton, very readily learns about the distance to leave his gate open, necessarily making the jig as near absolutely automatic as any jigging process that has ever been developed.

The coal, after having been separated from its impurities, passes over the top of the jig box d and out to j, into what is termed the settling basin n, where it is allowed to settle to the bottom, there being very little disturbance of the water in n; thence it is delivered by a perforated bucket elevator to any point desired.

The next important feature is the water circulation, the water being used over and over again. The only fresh water required is the water that is actually consumed or absorbed by the coal in the process of washing. The water from the basin n, which overflows from the top into a well is carried by any means desired — commonly a centrifugal pump on account of capacity and low duty — into what is termed the supply tank o, thence through opening p into tank e to valve q. As the jig box d moves up, the valve being a cast iron swinging check, admits the water through p into e and fills the vacancy caused by the upward motion of d. On the downward motion of the box d, the valve q closes and the water is forced through the perforated bottom of the jig box d and the same process is gone over and over as has been cited.

The gate in front of the jig box is left open at a certain point, which is governed by the amount of slate and impurities to the tonnage of coal being washed. The down motion of the jig loosens the slate bed in the bottom and works it toward the front, or discharge, side, where it is discharged into the jig tank e under the jig box and is carried by a chute or hopper to a point where it is taken up by the refuse elevator and carried out. The peculiar arrangement of this jig box with the perforated bottom fitted into the tank gives a very sensitive with which the jig distinguishes the difference between materials of a very close specific gravity; for instance, in one case where the coal varies in specific gravity from 1.29 to 1.37, the bony coal from 1.38 to 1.56. the shale from 1.40 to 2.04, and the slate from 1.70 to 3.40, an average from forty-nine samples of run-of-mine coal shows the coal, 82.6 per cent; bone coal, 11.4 per cent.; shale, 4.5 per cent.; slate, 1.5 per cent. The following is the result of eleven samples taken from the washed product: Coal, 92.9 per cent.; bone, 5.3 per cent.; shale, 1.8 per cent. The refuse or tailings show coal, 3.8 per cent.; bone, 18.2 per cent.; slate and shale, fireclay to contend with, mixtures of coals from three different places were washed.

Some base dimensions

The Jig Box was just a quick and dirty drawing without any real attempt to get any accuracy.  Note that the dimensions  were created through a long process of re-constructing the Washery and are basically .. what was left after fitting the other pieces together.

The Jig Box sits between the walls of the Jig Tank and has a maximum width of 1.396″ as shown. From the article above we have … “The jig tank e is built in size to suit the jig box so as to allow it to swing free. The tank is bushed in on four sides with iron plates to fit squarely against the same character of plates on the jig box, giving the result of a practically tight joint, but at the same time giving the jig sufficient play so that it can be moved up and down by the eccentrics f and g hung on the two pieces of shafting just over the jig.”

Looking closer at that .. we have

• The jig tank e is built in size to suit the jig box so as to allow it to swing free.
  • Right away the difference is that I will fit the Jib Box to the Jig Tank. The “… so as to allow to swing free …” –
• The tank is bushed in on four sides with iron plates to fit squarely against the same character of plates on the jig box, giving the result of a practically tight joint, but at the same time giving the jig sufficient play so that it can be moved up and down by the eccentrics f and g hung on the two pieces of shafting just over the jig.
  • For now I am reading this – “… tank is bushed in on four sides with iron plates to fit squarely against the same character of plates on the jig box …” to mean that plates are attached to a wooden box on both sides and front and back. Matching iron plates are also attached to the Jig Tank … so they act like vertical bearings between the Jig Box and the Jig Tank.

• • The front and back walls of the Jig Tank and the Jig Box are 0.091″, 0.092″, 0.087 and 0.085″. These average at 0.089″. Full-Scale this would be about 4″ thick (I sometimes forget how massive this structure is).
  • Circled in red are the iron plates mentioned earlier. Note that the plates on the walls (0.306″/about 14.5″ Full-Size) are twice the height of the plates on the Jig Box. That makes sense . in the drawing the Jig Box is at the bottom of it’s movement meaning that it can move up about.0.150″/7.2″ FS. Look at the eccentrics .. they have about a 0.130″/6.2″ ‘stroke’. The gap shows about 0.032″/1.5″ FS. Seems that 1/2″ plate would be about right.
  • In the Fig. Jig Width above we show that it is 1.354″ between the Jig Tank walls. Subtract the 0.032″ (x2) we get a Jig Box width of 1.29″/61,92 FS.

It measures w.306″/about 110″ FS. Subtract the 0.032″ (x2) and we get a Jig Box with a 2.242″/107.6″ FS length.

With that we can jump to the Jig Box