Sunday, October 16, 2016

Modeling mining, Part 2

In the first post in this series, I wrote about ways to find out whether there was any significant mining in the area you model, and some examples of what I have learned about chromite mining in the locale of my own layout. (You can read that post at: .) In the present post, I discuss modeling options and challenges.
     The first issue can involve layout planning, as to whether a mine can be included on the layout, and what it should look like. Most chromite mines were not very big or very deep, so did not have grand hoisting works, giant breaker buildings, or mammoth stamp mills. In fact, most of them trucked their ores to rail loaders, as in the Castro Chrome Company loader of which I showed the photo in the previous post. In that case, the truck distance was about 6 miles from mine to loader. Other mines described in the California Division of Mines report I showed previously had similar or longer distances of truck hauls. So my first conclusion is that a truck dump would be a good way to load chromite ore in my area.
     Second, what kind of ore would it be? I mentioned in the previous post that fairly pure chromite is a glossy dark brown or black color. But by the era I model, most of the high-grade or massive chromite deposits had been mined already. That means that mining would consist of disseminated ore, usually with some of the country rock with it, or reprocessed mine dumps, where modern methods could find additional low-grade ore discarded during mining of high-grade ore. There was also the reclaiming of what is called “float,” meaning ore chunks that have eroded from the top of an ore body and moved downhill in water courses. With a dense mineral like chromite, the float can readily accumulate at slower-moving parts of stream courses.There was extensive float recovery in the area I model, so that kind of ore might also move to truck dumps.
     I now plan to add a truck dump on the layout to permit loading of chromite ore. That modeling is not yet underway, but I have a couple of locations in mind. There is currently a Walthers kit for a truck dump (Cornerstone kit no. 4058) and I might use components of that kit for the dump. I’ll return to that in a future post.
     There was a company called Monarch Mining at one time in the central coast area, and it was involved in the chromite traffic. I can use Southern Pacific GS gondolas, as Mac Gaddis mentioned in the post cited in my previous post on mining, and showed in the Castro Chrome photo, or perhaps I could use an ore car or two in Monarch lettering. (I should mention that I have no evidence that Monarch in fact ever owned any railroad cars.)
     In a previous post (at: ) I showed a car lettered for Monarch. In the car, as described in that post, is a load intended to represent disseminated chromite ore. The actual material is crushed green shale, but it has the right hue to pass as the serpentine matrix rock of many chromite ores. Here is a repeat of that photo:

This is an O-scale Gilpin Tram ore car (offered as a kit by Grandt Line), simply given HO scale detail parts and trucks.
     I mentioned in the previous post, cited in the first paragraph at the top of this post, that chromite ore is pretty dense, 280 pounds per cubic foot. This sounds like a job for an ore car like the Mesabi ore jennies, 70-ton cars only 20 or so feet long, with cubic capacities ranging from 850 to 1250 cubic feet. But in fact iron ore is not as dense as chromite; 70 tons of chromite would only occupy 500 cubic feet. So even an ore jenny would not be filled with pure chromite, to stay within load limits. But disseminated ore, containing matrix rock as well as ore, would be less dense, and an ore car could be portrayed as entirely full.
     I still own a couple of kits for the old Model Die Casting white metal ore cars, and built up one of them to letter for Monarch Mining. I chose the reporting marks MMCX for this (there was no user of this mark in the year I model, 1953).

     My loads for cars like this have been shown previously (for example, in the post at this link: ). I make a base and apply paper mache to it to form the shape of the “heap” of bulk material for the car. Usually with these loads I leave a small gap at one end or one corner, and keep handy a small hook-shaped piece of wire that can be simply hooked under the load and lifted free of the car. In the photo below, one load is in the ore car, and two more are on the ground, one still just paper mache without the “ore” glued to it yet. At bottom right of the photo is a short wire tool for lifting loads, for example from the notch visible in the right end of the ore load in the foreground.

To illustrate the use of the wire took in lifting loads, the photo below shows this in progress.

     This technique with the wire tool is a simple and dependable process, and it allows loads to be built which fill the car. One sometimes sees quite undersize loads in use on some layouts, presumably for ease in removing them, but instead I would prefer to use a tool like this (or a magnet to attract a piece of iron glued to the bottom of the load), and have full-size loads.
Tony Thompson

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