Search keywordquery refinementfilter from URL

I am trying to pass a refinement filter that I am parsing out of the url on the search page. Essentially, I want to grab the criteria in the URL and pass it to a custom webpart that executes the search and spits out a csv. 

So on the url it looks like "r":[{"n":"Department","t":["\"??4875...\""],"o":"and","m":null,"k":false}]

Essentially Department is a custom refiner. 

How do I pass this to the keywordquery class using the refinementfilter property?

I tried keywordquery.RefinementFilters.Add("Department:\"??4875...\"") but it didn't find anything.

So two questions - 

1. Is there a parser for the search string url or do I have to build one from scratch?
2. How do I add the refinementfilter string correctly?

Thanks in advance,
Jake.