Looks like someone dropped the table which then landed on the handle, which rotated the shaft and the broken bit about the pin in the big hole, and broke off the end. Tables are b****y heavy, it's easy enough to do.
First disassemble it fully, removing the handle and shaft. Clean thoroughly, any oil will make most techniques fail.
I would then pin and bronze-braze it, but then I do a lot of brazing. Use a decent hearth and a *lot* of *slow* preheat, almost to dull red, followed by a soak at heat and a long slow cooling - but you'd need a minimum of a big gas/air torch or possibly two for preheat, and OA or TIG or AC/DCEN bronze stick for the brazing.
It is also possible to weld cast iron using nickel rods, but that's really only a job for the highly experienced.
Another option is fusion welding - first tack the pieces in position. Bodge up a furnace out of firebrick or something and fill with charcoal. Use a blower until the part is dull red, then turn off the blower and weld in the furnace with a CI stick. Thick gloves, that sucker will be hot! Add more charcoal, blow some more until not quite red hot, then cover it all with sand and leave for a day or two.
As you will have noticed, getting CI hot before welding or brazing is important, as is post-heat. CI is quite rigid and has low tensile strength, and heating portions to different temperatures will cause stresses through differential expansion which CI can't handle. Evenness of temperature is most important.
Having said that, in this case the cross-section is not very large, and as it's a straight through break, rather than a crack, most of the stresses will be in directions which don't matter that much, so you have a better chance of success than for most CI repairs.
Getting somewhat bodgier now. I don't know whether a hot domestic oven would do for preheat/cooling, but you could give it a try. If you have a weedwhacker or a similar powerful gas torch you could try that, especially if you can bodge up some kind of hearth to reflect the heat back in.
I'd try DCEN stick brazing first, run fairly cold (about 2/3 normal current) with a bronze rod, or AC stick if you don't have DCEN, rather than TIG. Borax will do for flux if you need extra or the rod is uncoated, and is cheap.
If you braze with brass rather than bronze it'll be harder (read: impossible) to weld it later if it breaks again. Thoroughly brush the prepared surfaces with a stainless brush before brazing, it helps remove the carbon layer which may prevent the braze wetting the CI.
If you can't pin it, tack or screw the parts together with a strip of metal to one side of the parts and braze the other side, then remove the strip (but see below) and braze the other side, keeping it as hot as you can all the while.
If there's room in the table you might also be able to reinforce it with some extra weld/braze/metal stuck on the outsides, including over the flat edge of the D which I think is where most of the tension is.
-- Peter Fairbrother