Mining screen device and grid structure therefor

A screen apparatus for separating solids from a drilling fluid, the screen apparatus comprising

• an outer frame having four interconnected sides defining a frame opening through the frame, the four sides including two pairs of spaced apart parallel sides,
• a plurality of spaced-apart support members each extending across the outer frame from one side to an opposing side parallel to and across from the one side,
• a grid structure secured over the frame and covering the frame opening, the grid structure comprising
• a plurality of spaced-apart first extending elements each extending across the frame continuously in a straight line and at an angle to sides of the frame,
• a plurality of spaced-apart second extending elements each extending across the frame continuously in a straight line and at an angle to sides of the frame and at an acute angle to the first extending of elements,
• a plurality of base extending elements extending across the frame parallel to two parallel opposing sides of the frame,
• the first extending elements-intersecting the second extending elements forming an acute angle therebetween so that with the base extending elements a plurality of open triangular openings are defined through the grid structure, each triangular opening having a shape of an acute triangle, each of a plurality of the base elements serving as the base for a first triangular opening and as the base for an adjacent second triangular opening inverted with respect to the first triangular opening, and
• a solids-filtering screen means secured over the grid structure and covering the plurality of triangular openings for filtering solids from the drilling fluid, the solids-filtering screen means comprising a first filtering screen with a first mesh opening size, a second filtering screen below the first filtering screen and with a second mesh opening size smaller than the first mesh opening size, and a filtering cloth below the second filtering screen.