If you're not averse to investing in the mining sector and want big returns for your portfolio, then read on.

That's because analysts at Bell Potter have just put buy ratings on two ASX 300 mining stocks and are tipping potential upside of 25% to 50% from them.

Here's what the broker is saying about these mining shares:

Bell Potter believes that this ASX 300 mining stock could deliver big returns for investors over the next 12 months.

This morning, the broker has retained its buy rating on the critical minerals developer's shares with a reduced price target of $3.30. This implies potential upside of 51% for investors from current levels.

Bell Potter highlights that the company has released its Woodlawn Restart study. The study looked at the resumption of operations at the Woodlawn copper-zinc mine in New South Wales over a 10-year period. Pleasingly, it delivered a pre-tax net present value of $658 million.

The broker is feeling very positive about the restart and notes that it is just one of many projects in the works. Overall, it feels this sets up the company to generate strong medium to long term earnings and free cash flow. It concludes:

DVP is progressing multiple critical mineral projects simultaneously, with each development representing an opportunity to transform the company's earnings and FCF generation profile. The most advanced of these projects, Woodlawn, is expected to recommence production in 1H CY25; FID and announcement of a financing package are important upcoming catalysts. The Sulphur Springs and Pioneer Dome developments represent medium to long-term opportunities to further grow earnings and FCF.

Another ASX 300 mining stock that could be great value according to Bell Potter is gold miner Regis Resources. This follows the release of a costs update from the 100%-owned McPhillamys Gold Project (MGP).

While its costs are forecast to be significantly higher than previous expectations, the higher gold price offsets this disappointment. It commented:

RRL's update guides to material cost increases compared with our prior assumptions, which included pre-production CAPEX of A$550m and AISC of A$1,440/oz. […] All else being equal, these increases would have had a significant impact on project returns and valuation. However, in the context of the spot gold price (A$3,550/oz) and our latest long-term gold price forecast (~A$3,200/oz) the MGP remains an attractive project. In reflecting the longer-dated development timeline (we had been expecting FID around end FY24) and the higher quantum of funding, we increase our risk-adjustment discount for the MGP. The net result is that our valuation is effectively unchanged.

In light of this, the broker has reiterated its buy rating and $2.60 price target on the ASX 300 mining stock. This suggests potential upside of almost 25% for investors from current levels.