Behat Mink webdriver session is destroyed after every feature in a suite
Features and scenarios should be independent. It is THE expected behaviour that if you do something in one scenario, the state is not carried to the next one.
I'm not sure what you're trying to achieve but you definitely doing something wrong.
Edit:
If you need to log user in before every scenario simply write a meta step which will perform all the necessary operations:
Given I am logged inYou could use step execution chaining or simply call Mink directly.
If every scenario in your feature file requires logging in you can use background:
Background: Given I am logged inScenario: Listing users Given ...Scenario: Removing a user Given ...