Yet, an expected deluge of deadline day deals failed to materialise with Everton the most active after also sealing a season-long loan deal for midfielder Andre Gomes from Barcelona and the capture of Brazilian winger Bernard on a free transfer.
Silva has been desperate to bolster Everton's defence all summer and had been linked with a number of targets, such as Manchester United's Marcus Rojo and Newcastle's Jamaal Lascelles, but Mina was his top target.
The fee represents a healthy profit for the Spanish champions, who signed Mina from Palmeiras for €11.8m (£10.6m) only in January and obtained a buy-back option in the deal.
Colombian centre-back Mina will join in a deal worth €30.25 million with another €1.5 in potential add-ons, Barcelona said.
Everton had an eventful deadline day, making no fewer than four big-name signings, including Bernard, Gomes, Kurt Zouma and Mina.
Everton, who finished eighth in the Premier League last season, have always been viewed as the side most likely to mount a challenge to break into the illustrious top six. "When I found out about this opportunity and what the manager wanted out of me I was happy". But I was also convinced Everton could improve me and that I would be able to show my best as a player here'.
In March, having endured consistent criticism for failing to live up to his Valencia form, the 25-year-old described his Barca spell as "a kind of hell", admitting he had struggled with depression.
"I spoke to Lucas and he told me all about the Club, which also made me keen to come here".
Another addition from the Nou Camp, midfielder Andre Gomes, joined on a season's loan.