Coal Washery

So – What IS a Coal Washery?
The following is take from “Surface arrangements at bituminous mines” Copyright 1907. from the Chapter titled “Coal Washing”

As coal is never found pure … the impurities contained need to be removed. The impurities such as slate, bone, iron and sulfur (in the form of iron pyrites), and the clay or dirt that is found with the coal. If the slate, bone, and pyrites are not too intimately mixed with the coal, they may be separated from it by the use of water, after the lumps have been broken into small pieces. The coal being lighter will float off, while the bone, slate, and pyrites will settle. This method of separating the impurities is called coal washing.

What that basically means is that there were many different ways of making what was essentially a giant washing machine. There was a need to crush the coal prior to washing it – but that is another subject altogether.

On page 67 there is a sectional view and a sideview of a ‘Stewart Jig’. The diagrams gave me enough information to start to re-create the structure in Sketchup.

In another book titled “Coke: A treatise on the manufacture of coke and other prepared fuels ..” Copyright 1905, I hit the jackpot as there are even better drawings and description of the Stewart type washery.

The drawing to the left shows what I started with. This along with the text allowed me to pretty much figure out where all the bits fit.


Washery Overview

Here is the washery as modeled in Sketchup. I left off all of the various machinery bits as I was concerned with the construction of the washery itself.

None of the joints are butt-joints but are jointed as they would have been in ‘real life’.

I’m going to sub-divide the Washery build into probably four sections. This is simply so I can make sense of what I am attempting and have no basis in anything other then that:

  • Section IOverflow tank – what it says .. overflow of water from the Jig tank. Settling tank – Where the coal and share separate. From this tank the cleaned coal will moved to the coal tipple where the larry will be filled from.
  • >Section II – Consists of two parts: A Supply tank – Filled with water continuously (recycled from the settling tank) and the Jig tank – an agitator. This is the working part of the Washery .. the agitation separates the coal and shale.
  • Section III – At the very top of the structure is the Unwashed Coal Bin – this receives the coal from the breaker via a conveyor belt. It will contain crushed and broken coal, shale, dirt and clay. A door and chute will allow the material to be processed as needed.
  • Section IV – All of the mechanicals. I may expand this to a fifth section depending on how complex this gets.
Logic and Guesses
For the next while I’m going to post up what I modeled in Sketchup.

I used the drawing from the book and then to the best of my ability how I interpreted that drawing. Where I couldn’t transfer that drawing to the 3d model I tried use logic. Not being in any way an engineer that ‘logic’ may be suspect. Feel free to comment on that point if you wish.

I expect at some point someone will point out that I have ‘Widget A’ incorrectly connected to ‘Widget B’. Be nice. I’m just a hobbyist doing my best and not .. as I said an Engineer. Simply explain why ‘Widget A’ should be connected to ‘Widget B’ and if I agree I will change it. See. Simple.

I haven’t started the model yet .. I’m just laying out the plan for it now.

I have nothing to go on other than I would guess the timbers would undergo the same procedure as bridge timbers from the same time period. Bridge timbers that are new are dark brown from creosote. When they have weathered over the years they are gray. I could *pressume* (close to an assumption with all the baggage that can have) .. that this will fall somewhere in between.

A little research shows that railroads used zinc chloride to treat ties in the late 1800’s, switching over to creosote in the first decade of the 1900’s. Since the references to a coal washery were published in 1905/1907 then we could suppose that either the wood wasn’t treated at all or if it were, zinc chloride could have been used. I did find where attempts were made to add a dye to zinc chloride treated wood to enable telling how deep the preservative had pentratiated .. which tells me that there must be little color change. I suspect that I will just .. make the wood gray after all and forget all of the ‘guesstamation’.

I was thinking about this a bit and with no supporting evidence at all I would bet that the parts that are in constant contact wtih water such as the tanks would have been tarred. If you think about it .. boat hulls were tarred .. joints between boards stuffed with oakum and then covered in pitch. I would be willing to bet that the insides of the tanks were mopped with hot tar/pitch.

Milling Stop
jigNo few pieces of the timbers will require a notch cut into the end. A simple stop as shown would enable me to run a 1/4″ Dremel Router Bit to make the notch. Since the only difference will be the distance the notch is from the end and the depth (which honestly will probably be the same 0.042″) I will need to note which timbers need to be grouped for the same cut. Let’s call this .. ummm .. NG or Notch Group(ing). So .. say a notch 0.042″ deep, 1/4″ wide that is 1/8″ from the end will be NG-1. I will annotate the drawings with that.
Next - Section I


Coal Washery — 4 Comments

  1. Hi, my name is José, I’m looking for the book “Surface arrangements at bituminous mines” (Copyright 1907 or subsequent): can anybody help me find it, please? Thanks.

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