diff --git a/src/lt/nogalosa/nercoin/Main.java b/src/lt/nogalosa/nercoin/Main.java
index b67609f..ff600be 100644
--- a/src/lt/nogalosa/nercoin/Main.java
+++ b/src/lt/nogalosa/nercoin/Main.java
@@ -3,10 +3,12 @@
 import lt.nogalosa.nercoin.entities.Block;
 import lt.nogalosa.nercoin.entities.Miner;
 import lt.nogalosa.nercoin.entities.Transaction;
+import lt.nogalosa.nercoin.hash.NerHash;
 import lt.nogalosa.nercoin.managers.TransactionManager;
 import lt.nogalosa.nercoin.managers.UserManager;
 
 import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.Random;
 
 public class Main {
@@ -17,15 +19,36 @@ public Main() {
 
         UserManager.i().generateUsers();
         ArrayList<Transaction> randomTransactions = TransactionManager.generateRandomTransactions(UserManager.i().getUsers());
-
-        Block block = new Block();
-        for(int i = 0; i < 100; i++) {
-            Transaction transaction = randomTransactions.get(random.nextInt(randomTransactions.size()));
-            block.getTransactionManager().addTransaction(transaction);
+        ArrayList<Block> blocks = new ArrayList<>();
+
+        for (int x = 0; x < 5; x++) {
+            Block block = new Block();
+            for (int i = 0; i < 100; i++) {
+                Transaction transaction = randomTransactions.get(random.nextInt(randomTransactions.size()));
+                block.getTransactionManager().addTransaction(transaction);
+            }
+
+            Iterator<Transaction> transactionIterator = block.getTransactionManager().getTransactions().iterator();
+            while (transactionIterator.hasNext()) {
+                Transaction transaction = transactionIterator.next();
+                if (transaction.getFromUser().getBalance() < transaction.getAmount()) {
+                    block.getTransactionManager().removeTransaction(transaction);
+                    System.out.println("Removing " + transaction.getHash() + " #1");
+                }
+
+                NerHash nerHash = new NerHash(transaction.getFromUser().getPublicKey() + transaction.getToUser().getPublicKey() + transaction.getAmount() + transaction.getTimestamp());
+                if (!nerHash.hash().equals(transaction.getHash())) {
+                    block.getTransactionManager().removeTransaction(transaction);
+                    System.out.println("Removing " + transaction.getHash() + " #2");
+                }
+            }
+
+            block.setDifficulityTarget("2");
+            block.generateMerkelTreeHash();
+            blocks.add(block);
         }
-        block.setDifficulityTarget("2");
-        block.generateMerkelTreeHash();
-        Miner blockMiner = new Miner(block);
+        System.out.println("Starting miner with "+blocks.size() + " blocks.");
+        Miner blockMiner = new Miner(blocks);
         blockMiner.start();
 
     }
diff --git a/src/lt/nogalosa/nercoin/entities/Block.java b/src/lt/nogalosa/nercoin/entities/Block.java
index 2c49d32..4357dd1 100644
--- a/src/lt/nogalosa/nercoin/entities/Block.java
+++ b/src/lt/nogalosa/nercoin/entities/Block.java
@@ -15,6 +15,7 @@ public class Block {
     private int nonce;
     private String difficulityTarget;
     private TransactionManager transactionManager;
+    private boolean mined;
 
     public Block() {
         transactionManager = new TransactionManager();
@@ -84,6 +85,14 @@ public String getHash() {
         return hash.hash();
     }
 
+    public boolean isMined() {
+        return mined;
+    }
+
+    public void setMined(boolean mined) {
+        this.mined = mined;
+    }
+
     public String toString() {
         return getHash();
     }
diff --git a/src/lt/nogalosa/nercoin/entities/Miner.java b/src/lt/nogalosa/nercoin/entities/Miner.java
index 64844bd..5d51b88 100644
--- a/src/lt/nogalosa/nercoin/entities/Miner.java
+++ b/src/lt/nogalosa/nercoin/entities/Miner.java
@@ -1,18 +1,40 @@
 package lt.nogalosa.nercoin.entities;
 
+import java.util.ArrayList;
+
 public class Miner extends Thread{
 
-    Block block;
+    ArrayList<Block> blocks;
+
+    ArrayList<Block> mined;
 
-    public Miner(Block block) {
-        this.block = block;
+    public Miner(ArrayList<Block> blocks) {
+        this.blocks = blocks;
     }
 
     @Override
     public void run() {
-        while(block.getHash().compareTo(block.getDifficulityTarget()) > 0) {
-            block.incrementNonce();
-            System.out.println(block.getHash() + " > " + block.getNonce());
+        int currentTries = 1;
+        int currentBlock = 0;
+        long lastTimestamp = System.currentTimeMillis();
+
+        while(blocks.size() > 0) {
+            if(lastTimestamp + currentTries * 1000 < System.currentTimeMillis() || currentBlock >= blocks.size()){
+                currentBlock++;
+                if(currentBlock >= blocks.size()) {
+                    currentBlock = 0;
+                    currentTries++;
+                }
+                lastTimestamp = System.currentTimeMillis();
+            }
+            if(blocks.get(currentBlock).getHash().compareTo(blocks.get(currentBlock).getDifficulityTarget()) > 0){
+                blocks.get(currentBlock).incrementNonce();
+                System.out.println(currentBlock + " > " + blocks.get(currentBlock).getHash() + " > " + blocks.get(currentBlock).getNonce());
+            } else {
+                System.out.println("Mined: "+blocks.get(currentBlock).getHash());
+                mined.add(blocks.get(currentBlock));
+                blocks.remove(currentBlock);
+            }
         }
         System.out.println("Success!");
     }