I'm trying to build a rather large desk that's going to hold 2 computers 2 monitors and accessories associated with them, and well, 2 humans working all day long and occasionally resting on the desk.
I've already picked the countertop, which is a 2000mm/600mm/28mm in size made of highly compressed chipboard but it's still relatively heavy.
It's going to be wall-mounted to a red-brick wall that has some plaster on it but I intend to use dowels with steel screws (black ones) and 3 triangle shaped steel corners positioned at both ends and in the middle.
Thing is, I don't know what length the screws should be and currently I have trouble finding steel triangle that goes at least 300mm in width and to me it feels like the whole thing would just be unstable. The countertop is sort of heavy. It's not real wood but it still weights something in the ballpark of 10-15kg (could be wrong, just feels very heavy)
I also noticed the stores sell L-shaped corners but I don't know how they distribute weight to the wall.
Eventually I considered using table legs but you know … the desk would lose it's wall-mounted spirit, but even with that I think of using at least 1 leg in the horizontal and vertical center of the plot.
I'm not an engineer nor an architect and I'm wondering what maths should I use to calculate things properly to get a stable and sturdy desk. Sure I won't sit on it, but my guests could and it has to hold 2 Full-ATX computers and screens to them.
Is it even possible to have this wall mounted or I'm better of with 4 legs (although it's an issue finding legs with the height I need so I guess I'll have to order some custom ones, which is expensive).
Thank you for any advice.
EDIT NOTE: On the diagram, the triangles are 180mm not 18mm !!!!!
Side diagram: 
EDIT: I was considering adding legs and make it as a combination but do I add 2 or 3 legs? The material doesn't bend much, if at all, it's a work countertop but I don't know. And If I get 3 legs, first, my chair is going to bump into it sooner or later and second … if I get 3 legs … why not just go for 4 legs. I mean … 4 legs is going to cost less than 3 legs + 3 steel braces. Minus the issue that I can't find legs with the height that I'm looking for.
Best Answer
This is perfectly feasible, but you need different brackets. They should extend at least 2/3 of the way to the front edge of your table and be about 2/3 as tall as they are deep, at a minimum. There are a number of similar questions on DIYSE which may give useful details, but the gist of it is to use heavy-duty brackets and robust fasteners.
I don't know what "black screws" are, but I recommend 8mm (5/16") lag screws in purpose-built anchors, carefully placed in solid portions of your wall and penetrating at least 5cm (2"). For a 2m desk I'd use four or five such brackets, with all provided holes filled with screws.
You'll need to fasten the top through the brackets as well, particularly at the rear, to prevent tilt. Use thick screws that penetrate about 3/4 the depth of the top, and pilot appropriately for them. A wrap of tape on your drill bit to indicate depth will prevent catastrophic mistakes.
If either end of the desk contacts a wall, install cleats to carry the load there. They'll add considerable stability to the top. Keep the front ends back a few inches so they don't show, and you can taper the end cut back as well.