Depends on lots of things.
Heap should be less than 0.5 kg/t. Might be higher depending on what else is in it.
Vat - low would be less than 1.0kg/t, moderate between 1 to 2 kg/t, high would be more than 3kg/t.

You can try to calculate any theoretical cyanide consumption for your ore. To do this, you calculate the theoretical consumption according to the reaction equations. Then, this consumption is increased by 10%, since part of the cyanide is consumed by side reactions and hydrolysis. The resulting figure can be laid as a starting point for test tests. Then you select 3-5 points with a certain step, to work out different concentrations.

Usually, the starting point is chosen to be 0.05% NaCN. Then take 0.025; 0.1; 0,15; 0.2%. For the initial ore, this is usually the optimum concentration.

Always NaCN basis.  Make sure what ever you are using to measure the cyanide concentration is also on this basis.  Heaps agree probably start the leach at 500ppm and then control to 250ppm.  

I am old fashioned, I always do this with either a bottle roll or a column leach. I put 4 or 500 grams in a bottle, with the amount of water to get you the per cent solids you want, lime, caustic or what ever to get you pH of about 10 then add an excess of cyanide again I am old fashioned and add about 2 # per ton of ore. Put this on the rolls and pull a sample every once in a while, I do every 8 hours for as long as you are planning on agitating. You simply titrate the solution and record your number and as long as there is cyanide available and your pH is at or slightly above 10, you continue, if you run out you add more. You can also assay your solution and see how you are doing recovery wise. When you finish it is easy to calculate how much cyanide and pH control material you used. You can then run other test and you use just slightly more than you calculated the ore used up. To me this is a very simple way to do this and it has worked for me for over 60 years.