The minimum land for setting up an icecream factory depends on where you want to apply for it. The criteria is not similar for different states.
What I can tell you is the infrastructure needed for it will be as follows:

• Refrigeration compressor (open type): 5 TR capacity complete with motor and accessories.
• Cooled condenser complete with piping and water spray assembly.
• Liquid receiver
• M.S. Brine tank
• Agitator fan assembly
• Thermocole
• Push Cart trolleys
• Ice-cream freezer complete with an extension including valve, shut off valve etc.
• Electrical including motors: Complete set ranging from ½ to 20 hp
• Mechanical accessories such dehydrator with the complete set suction line, copper pipe, liquid distribution, pipe, shut off valve etc.
  For a small plant, you need to invest 15 lakhs to 20 lakhs.
  Good luck!