You have a lot of options, but many will be impractical for your purpose. I will list some of them here:
- ICO - I would say you should disregard this as a possibility unless you have a coin you can offer, a team to develop the coin, and a practical application that you are trying to tackle.
- Traditional Venture Capital - This would be difficult to acquire unless you demonstrate how you're mining farm could capture a massive market and produce huge profits. I would say this is unlikely and not to mention most VC firms don't want a return on the profits, they want a return when the company goes public and they can sell your stock post IPO (or when you get acquired).
- Business Bank Loan - This is probably the most practical of the options, however, it would of course require you to repay the loans. If the value of BTC falls or mining becomes less profitable, this could mean you have large loans you must repay.
- Angel Investor - This is another practical option. Many angel investors are similar to traditional venture capitalists in that they would expect equity in the company, however, you may be able to negotiate a percentage of the profits instead. I don't know how much investment you are looking for, but I would say you could expect anywhere from 10K - 50K from reasonable angel investors.
- Crowd Funding - There may be crowd funding resources similar to Kickstarter which allow for project creators to share the profits. I haven't looked into this, but it's quite possible. This would be a good bet if you can create a successful marketing campaign and demonstrate the potential profits of your business.
There may be more funding options, but these are the ones I usually look at when starting a new project. No matter how you attempt to get funding, making a strong business plan is important. Create documents which lay our your profits to date, how much you've spent on the endeavor, what your growth potential would be in the future, etc.
Best of luck!
