Take a look at the Wiki on the page Mystic Forge. It will tell you where the forge is, how it is used, and some predictable recipes. The forge lets you do two things. First you can create recipes to craft other items like consumables, weapons, or armor. Second, the forge can be used to create better crafting materials of one type higher.
The examples the wiki gives are as follows:
Common Crafting Material Promotion
Common crafting materials can be promoted to a small pile of higher
tier materials with the following formula. The tier of dust needed is equivalent to the tier of the wanted product. So, if you are hoping to create Orichalcum, a tier 6 common material, you need to use Crystalline Dust, a tier 6 dust. If common crafting material B is one tier higher than common crafting material A, then:
10-50 Crafting Material B = 250 Common Crafting Material A (i.e. 250 Mithril Ores) + 1 Common Crafting Material B (i.e. 1 Orichalcum Ores) + 2-5 Dust A (i.e. 5 Pile of Crystalline Dust) + 5 Philosopher's stone
In that example: That recipe will produce 10-50 Orichalcum Ores
Armor boxes and armor satchels
Recipes can be created using the Mystic Forge. They will allow you to
craft armor boxes and armor satchels, which will in turn give you
every piece of an armor set.
Armor set recipe
Ingredients
5 Bottle of Elonian Wine
20 Arcane Crystal
50 Mystic Coin
1 Armor item
Mystic coins seem to be a common item needed for Food Trays, Weapons and Armor. Also look at this page for current recipe research.
You can see this in action with this video on how to make a Giant Chocolate Cake. Details are in the video summary.
Best Answer
There is a more or less hidden wiki article on the Black Lion Chest Drop rates, which is a user-curated list of drops, totalling 886 chests. Due to changes in the drop chances with patches, I would not trust on the reliability of this method.
A better way to check current droprates is to look on the Guild Wars 2 subreddit for posts of people mass-opening chests. According the most recent one documented on the Guild Wars 2 subreddit, there was an increase in drop chance after the then (April 1st, 2015) most recent patch.
Opening a total of 350 chests yielded 132 scraps and 7 full tickets, for an effective total of 202 scraps. This would place the effective droprate at around 57.7±4.1%. The error estimates here assumes that 350 is a big enough sample size for a Gaussian distribution (square root error).